I never beat this game as a kid and now I want to try it with the wisdom I have at 40.
A couple noob questions

1) How do I save the game?
1a) How do I save scum?
2) How do I rest and replensih my spell points?
3) How does combat work? Some of my guys had no option to attack even though they had a weapon. Is it only certain slots? ranged/melee?
4) How do I loot? I beat some rangers who nearly killed me, but I seem to have 0 gold
5) Can I slow it down? The screens where it said what dmg was done go by too quickly for me to read

1. The game saves whenever you enter the inn (where the game starts and you choose your party) and sign in; that is the only place you can save.
1a. I don't like the term "save scum", but if you want to erase everything, just reboot the computer you're playing the game on (there's no quit option because games back then weren't designed to run under multitasking OSes). If you are playing on an emulator (this includes DOSBox, which the GOG version runs under), close the emulator and restart it, or (for non-DOSBox emulators) there might be an option to reboot in the menus or via keyboard.
2. Press R outside of combat. Note that you must have enough food for everyone, and enough money to pay any hirelings that are currently in the party. (Note that this is the only time you need to eat or pay hirelings.)
3. The number of characters who can engage in melee combat is random, though terrain might play a role. Each battle, the first n characters (n being random) can fight in melee, while the rest instead can use ranged attacks. Archers (and only archers) can shoot from any spot in the party; other classes can't shoot from melee. Note that you can equip both a melee weapon and a ranged weapon at the same time.
4. After battle, press S to search. It won't work if you have moved (I am not sure whether movement by spell counts as movement for this purpose), but you can perform other actions such as resting before you search. Note that certain squares with treasure will only yield the treasure if you search; if this is the case, generally the game will tell you somehow (like with a sign, for example).
5. Outside of battle, press C to get the options menu (according to the manual I found online). Note that enabling sounds slows things down, as the game has to wait for the sound to play, so you might eventually want to disable it.
Pressing D during combat should also work.

There is an unofficial DOSBOX version which supports savestates. There were several such versions, I too will be very happy to know which is the best and most reliable, and MMt/2 are one of the reasons why I am interested in those DOSBOX versions.

I would say definitely give the manual a read through. It's not that long, and it addresses all the questions you posed; although dtgreene already did a good job answering them.
Also, as for who can attack in combat, you will notice that before each of your character names there is either a check mark- or not one. The check mark denotes who can fight in combat, and it changes depending on the terrain you were on when you got engaged in combat. For example, if you are in a narrow corridor, only the first few characters will be able to attack, but in an open square on the world map, everyone can fight. Or something close to that.