As far as I know:
1) Yes. Crit chance of skills is your crit chance. Well except Backlash which always crits.
2) Two-Handed increases your damage whenever you're wielding a 2H weapon, so all of your damage (with basic attack and weapon skills) is increased, whether crit or not.
3) Damage of Warfare skills is based on your basic attack damage. So if you're using 2H weapon, and invest points in Two-Handed, your basic attack damage is increased, thus the damage of your Warfare skills is also increased. This can be easily checked by reading the tooltips of the skills - you can compare the damage stated in the tooltips before and after you add points to Two-handed. You can save the game before doing that just in case you want to add points differently.
4) No. Torturer only works with damage over time effects, like Burning or Necrofire. Shocked and Chilled are status effects only, no damage, so no.
5) To trigger Affinity with Hydro, you need to stand in water or on ice. You don't necessarily have to use Rain, but that certainly works. Water Balloons work. To trigger Affinity with Air spells is trickier, you need to stand in electrified water. So you need water first, then electrify it, then stand in it. I haven't seen it, but I'd guess that electrified blood works, too.
Last edited by Try2Handing; 19/10/17 12:24 AM.