I also using Braiins and seems to be alright, this allows you do redirect some hashrate for solo.

 Higher performance for difficulty is fine, an S19 or above can do it but if you just have a single rig for part time then stick to 3333. Point of high difficulty is for big rigs of multiple miners that would otherwise take up pool resources, in the end is doesn't make any difference towards you solving a block.

 For the addition you can still use your same personal wallet address (never mine to an exchange) and just give them a name if you like to see how each is doing. Otherwise to the same wallet, it doesn't make a difference if you use the same wallet or use a new one for your second ASIC. Odds will remain the same whichever way you roll. It's a big raffle and every ASIC that is able to contribute 1 hash can be drawn!

good luck.

here is hoping for you