CHA and Bards
 

Does CHA effect bard charm/mez? If so what else does it affect regarding bards.

Charm/mez and buying/selling from merchants.

would it be overly beneficial to CHA-out my bard to 200+ CHA? Would that make charm a superior means of soloing as opposed to dd/dot kiting ?

Charm is the superior means, regardless of your CHA. I soloed lvl 29-50 with a CHA of 127.

I would attempt to maximize CHA after you've already maxed out DEX and STA.

what insturment affects bard charm and what are some decent magical version thereof?

Charm is normally stringed (from 15 to 30) or wind (28 onwards) based. Also lulls are based on the same instrument mods. Gypsy Lute from MM and Lianna's Flute from NK are good choices.