For OH, all of COLL is worth it, as well as all of ZBLL. I wouldn't recommend forcing a cross on the time, I would recommend switching to ZZ-z rotation for OH, as in the long term, it's objectively better then CFOP.
ZZ-z rotation yes. Lower movecount, only one rotation and that's z, better LL and all F2L is RU.That's not true, there's no proof that ZZ is better than CFOP at OH
No guarantee of this unless you force the first block's pieces to not be on the left side. Also, unlike regular ZZ, you can't mix up the orders in which you solve the first block and the second block, which actually hurts efficiency (although in practice I rarely switch sides, so maybe this isn't a big issue).all F2L is RU.