I am doing NMZ and was wondering is it faster to get XP on normal or hard? Does hard have better defence bonus etc?

hard is higher xp per hour because they have more hp, so ur switching targets less.

Can check stats of bosses on wiki, I don't think their defence changes

this is correct, also there are 4 bosses that give bonus xp / 1 damage done, the ice king troll, aarg, dad.... and i wanna say the fourth is king roland but im not entirely sure.

so for xp gains you can hit around 150k/hr with those four and another simple boss.

for some reason this info isn't on the wiki, couple youtube vids of it though

dclaws/gmaul for power surges, pray piety

moss giant
sand snake
ice troll king
count draynor
arrg