1)for question 1 i assume u mean the after joining the undead you got the book on necromancy and that after each battle you win you gain some new troops? if so then yes they cant be upgraded
2)i dont understand question 2 sorry
3) are you asking if there is any weapons that can be found by fighting? you cant get the special equipment for each kingdom by buying them like the feron weapons and i think some MAY be found through fighting but again certain items cant be found like feron weapons inquisitor armor, inquisitor swords etc.
hope that helps