RealGM

Seems like they changed the key size, so this is no longer relevant.

FIBA does have shorter quarters (although less time-outs) so maybe still some advantage to bigs?
Is the defensive side allowed to camp the restricted area?

I dont think so, smalls still dominate FIBA rules, shorter 3 point line helps them even more, offensively speaking.

Defensively, yes, it is much easier to be a traditional big in FIBA, because of no defensive seconds. Defense makes it harder for slashers, slashing guards are just more successful in the NBA, thats definitely the case.