1. just take my word for it.
2. if you care about improving bench, then you should bench. DB benching and actual benching are not the same exercise. so yes, i'd bench both days. just do 3x5 both days. start light and add weight every workout until you can't anymore, then add once a week. ride newbie gains as long as you can and only get complicated when you need to.
3. haha, it's not a bad idea to have a lower body pulling exercise like DLs but i don't think it's necessary given your goals. put everything you've got into those squats and let the assistance work be assistance work.