Do deadhangs at the end of every workout (including non-forearm day) and instead of DB curls, do reverse barbell curls. Instead of one of the tricep exercises you could do wrist curls.
I don't think you can isolate the muscles in this way. Try doing any of the above activities without biceps and you won't get very far! They work in partnership; although certain movements will...
You should try wrist curls and reverse wrist curls. Use 15-20 reps for 3 sets each. If you experience any pain then you should see your doctor and don't do exercise that causes the pain until...
First things first. Start to track your macros. You need to be in a positive calorific balance to gain any sort of muscle. Essentially this means finding how many calories you need to maintain...