So at the start of the game, you can pick spellbooks and skills.

From what I have learn so far, you can find new spellbooks during the game.

But is it possible to learn new skills during the game?

For example, if you did not pick Warlord or Alchemy at the beginning of the game, can you learn those skills during the game?

If not, then it is better to select more skills over spellbooks?

What is your opinion?

As far as I know you cannot find skills in the game and you can only find a maximum of two spell books. Have a look at the appendix in the manual (attached pic). How many spell books you have determine how many spells of each rank you can research. There are some very useful rare and very rare spells out there so I would want to take enough books in a school to have a good chance of obtaining them. I suppose it depends on your playstyle. Taking all 11 spell books in one school does net some pretty awesome abilities (reduced spell cost) but then again there are also some very useful skills (I like channeler in particular). In my last hard playthrough I took :8 nature + channeler + nature mastery.
I was very lucky to get Gaia's Blessing (to deal with a death wizard's Corrupted lands spell, and to create large cities), nature's wrath (to counteract the extremely annoying Meteor Storm global enchantment of a Chaos Wizard) and of course : Great Wyrm!

edit: and Call Lightning saved my rearend several times (also a very rare spell)

This is WRONG.

You CAN find new Skills/Abilities/Retorts, whatever you want to call them, like Warlord, Alchemy, Node Mastery etc... HOWEVER your Wizard can only have a MAX of 6 Retorts. Also you CAN also find Spell Book but you can only have a TOTAL of 13 Spell Books in all.

Things to keep in mind though regarding finding Retorts is the number of picks they need. For example Warlord costs 2 picks so would need a fight (Usually highly guarded Nodes) that would reward it. Keep in mind that a fight that would get you 2 spell books could get you Warlord instead, or 1 Spell book and Alchemy OR Alchemy and another 1 pick retort like Archmage. The only Retort you cannot get as a reward is Myran, which is good because it wouldn't do anything for you after the game has already started.

EDIT * Also when getting Retorts as rewards it ignores the normal rules that you would have had to follow originally. For example to get Node Mastery at the start of the game you need to have 1 book in each Chaos, Nature and Sorcery. This is NOT needed to get it as a reward though. Even more annoying is you could have say all Sorcery Books and find Chaos Mastery :( . Even more funny than that are Divine and Infernal Power, which normally need you to have either 4 Life or 4 Death books, but you can actually have Life Books at the start and later get Infernal Power as a reward, you can even get BOTH although this does nothing to benefit you.

Also finding the Artificer retort later in game will NOT give you the Enchant Item and Create Artifact spells that it would if you chose it at the start. Spell Book giving discounts actually starts at 8 books and goes up by 10% per book. At 13 Books it would give you 60% reduction in both casting and research costs. Check out my Spell Book Cost Discounts thread here for more info.

http://www.gog.com/forum/master_of_magic/spell_book_cost_discounts

Oh? did not know that you could find actual retorts in the game - that is interesting. It must be quite rare though. Heavily guarded nodes with very rare fantastic units usually net me some high level item. So I suppose in principle I could save/reload until I get a retort then. Probably won't though: Now that I've managed to beat hard (insecticide) at least once, I can move onto Age of Wonders with a clear conscience :)

You can find retorts but as I said since they are random and you can only have max of 6, it's really not the ideal way to get the ones you want.

Also if you find an encounter that rewards you with a Spell Book you can reload the fight to try for a 1 pick retort.

NOTE if your playing insecticide you cannot reload for a better pick as they stopped that along with reloading for a better hero via summon hero/champion.

Oohh that isn't good news at all :P I was up to now pretty sure I did play insecticide, however I definitely did get different items upon reloading a difficult encounter at a node (such as when winning but losing my hero).

Easy way to see what version your playing is to check on the Save/Load Screen at the bottom near the right side. The version you get from gog is v 1.31 and is the official version.

V1.4...etc is the fan made MOD (they call it a patch but it's more a mod as it doesn't just fix things but changes things to work like they think it should) called "Insecticide". The Mod/Patch thing is just a little pet peeve of mine. Patches are only supposed to fix bugs not rewrite things imho. Like the computer being able to attack you without declaring war but it not working the other way around.

Hmm it does in fact state that it is v1.4 so that is a relief. Perhaps I used a different version of the insecticide mod.

Actually that's a myth. It may have been disabled in a previous build, but in the most recent Insecticide reloading to get different treasure or to summon a different hero works just fine.

Scummers rejoice!

The trick with retorts (as they're called in MoM, although I don't really know why), is to pick ones with powers that stack or work in synergy with others you have. For example, Node Mastery doubles the mana you can get from nodes, and Nature Mastery gives another bonus to mana you get from nature nodes, so if you have both of those you'll get a whole heck of a lot of mana from any nature nodes you own. There are several different combinations like that (the most famous one is undoubtedly Artificer/Runemaster, but since you're playing MoM and reading this board you don't need me to tell you about it here).

Just to be clear on the reloading for to get a better hero with Summon Hero/Champion, can you reload just before the spell finishes casting OR do you have to reload from before you started the spell?

In the normal version, which you get from gog, you can reload to the turn before it finishes casting for a better hero.

According to the insecticde readme change file this was "fixed" in version 1.40 L, it is now at version 1.40n but I do not see anything stating they turned it back to the way it was in Vanilla.

http://koti.mbnet.fi/ton_hur/files/mom/MoM_Unofficial_patch_Readme.txt

"-it is now impossible to get better hero by reloading before a summon
-it is now impossibe to get better reward from lair by reloading before the battle"

Just before it finishes.

So there's no need to give up your Malleus addiction.

I find MoM much better now that I don't reload when something I don't like happens. I'll generally only reload if I make an absolutely stupid mistake or my hand slips or whatnot.

On the subject of retorts, I find that I always get my retorts and spellbooks maxed out when playing on Impossible 2.5x nodes. But while you can basically count on getting the sorcery/chaos/nature books from tough nodes, retorts are totally random so in that sense they've definitely more valuable than books.

Actually I prefer the term "save skimming," thankyewverramuch. "Scumming" just sounds so, well... scummy. :p

Well, you'd get the extra 5 mana per turn that it provides, but I doubt that would be worth giving up three picks worth of other books/retorts, especially at the stage of the game where you're clearing those sites!

FTR, you can also effectively duplicate this by using the rare Nature spell Move Fortress to, well, move your fortress into any of your Myrran cities. Doing so also recalculates your interracial rebellion penalties, since whichever race built the city your fortress is currently in becomes your new default race.

If you don't have that spell, then Plan B is to let your fortress get overrun, and then cast the Spell of Return. In doing so, you get to choose which of your remaining cities you return to, with the same benefits and drawbacks as above. Plus of course, whatever losses you happen to have incurred (magical and otherwise) during your hiatus.