2. Like I say, practice to get the balance right. It's not going to be totally stable. Make sure the wide-grip attachment is right up near the plates on the bar so you can at least get as much stabilisation as possible.
3. It's like touching wood for luck.. as in, I hope what I just said doesn't happen to me lol.
3a. If it gets painful, it's probably going to be painful on your forearms depending on grip strength. Depends on the bars too. And yes how much your lifting. Again.. try it for yourself and see would be the best way to see if it's going to hurt you or not.
3b. Monkey grip doesn't involve the thumb as much, so could have less change for having issues there. I personally don't think it's as strong as a regular overhand grip with thumbs wrapped around the bar.
4. That's great!
5. Both paused and regular touch and go reps on bench are good. Pause reps tend to help more towards building strength. It will take more effort because you're stopping and having to re-engage your muscles to inititate the movement again without bounce or momentum.