I tried searching but came up with nothing. I've several things which are confusing me so I'll just number them.
1) Items have a race property but what does it do?
nothing much really just the race who created it
2) A couple times now I've gone to a shop and then come back later and suddenly they have new units. What causes this? Is it level based or some such?
when u complete some main quest(getting more stones) after 2-4-6-8 you get new units at some place(most notable is the starting castle)
3) Do units ever restock? I was able to buy 4 royal thorns at one point but now none of the shops I've discovered has them.
shops never restock, sometimes castles do after completing some quest
4) Say a battlefield chest has an item in it and the enemy grabs it first. Will I get the item when I defeat them?
if an enemy gets it, the chest is gone for u

u will never get what was in store there xD
That's all the questions I can remember right now but I'm sure I'll have more soon. Thanks to anyone who can offer some help.