Orcs and Trolls

[Halbarad]

1/.Fangorn once said that the Trolls were made in mockery of ents, just as the orcs were made in mockery of the elves. Given that orcs were twisted elves, doesn't it logically follow that trolls would be from twisted ents, and therefore have some of their attrubutes such as strong skin (such as the cave troll in Moria). As arrows only infuriate ents, I think that trolls wouldn't be particularly bothered by them.
2/. Are we talking equal numbers here? 100 orcsa versus 100 trolls would be an unfair fight- trolls are huge and if they swipe a small tree trunk in front of them that would damage a large number of orcs. Granted trolls are stupid (unless they're Olog-Hai) but that does not work to their disadvantage unless they were ambushed by orcs.