To correct and explain:
1) Yes, more peasant huts increase the peasant spawn rate. Tried and tested. The videoproof is here
2) Yin/Yang points increase the damage of Zen Masters, including Ninjas/Monks and Wildeye's Spirit Wolves. Other units are not affected.
3) As explained in original Battle Realms Manual, the farther you fight from your base, the more points you get. There's no detailed information that would determine the certain regularity. BRJokerz go by one motto "The better you play- the more you earn", you get points for dealing damage to units and buildings. The more points you earn, the harder it is to get them.
Upgraded Town Squares give the clan 50% Yin/Yang raise boost.
The Dragon Clan has a special tactic of sacrificing samurais near their enemies, to earn the Yin points quickly by commiting seppuku (that's a game bug by the way, but nobody seems to care).
~ Peasants are equal in their building speed, and the training for them is equal too (Unless you speed them up with Issyl's or Budo's abilities). Wolf Peasants deal more damage (And will have more hitpoints, if ugpraded specifically) and gather rice faster, where as Lotus' peasants have the least hitpoints (135, unlike other peasants' 156).
Tier 4 units such as Werewolf and Master Warlock have certain conditions. Werewolf Requires a Berserker being blessed by Druid, Master Warlock requires 2 Warlocks, fightiing each other in the Warlock's Tower. So, depending on your speed, the time may vary. Consider the cost of buildings and units all combined.
The Necromancer, not a tier 4 unit, but a Zen Master, needs 4 Ronins sacrificing themselves near the Necromancer's Throne. Same as The Dragon needs 4 Samurai to sacrifice themselves + 3 Yin Points, but it won't move anywhere, it will deal huge AOE damage on the targeted area once you order.
The more you know, folks! Battle Realms is much more detailed, than it seems. ;)