SS Mesh comes in a lot of different sizes. Mainly 325, 400 and 500. In 304 and 316 materials.
As for wire there are quite a few types and sizes people use. Such as:
Kanthal A-1 (there is also B, C and D grades)
Kanthal D Ribbon
NiChrome-60 and 80
.999 Silver
Nickle (No Resistance)
Most people go with Kanthal A-1. It's really personal choice. Bigger wire allows more current to flow through thus
less resistance. The smaller the wire, the harder it is for electricity to flow through, thus more resistance. The higher
the number, the thinner the wire is.
If you're using a VV/VW Mod stick with 32g or higher. If not you'll error out and it won't fire. If your on a Mechanical
Mod you can go with lower resistance wire.
Patience is key. Believe me when I say it WILL take a while to get the hang of it. It's not an easy jump. Keep a tank full
with you while you practice, because your first couple wraps maybe even your first couple weeks will be trial and error.
It is worth it though and you will do a victory dance when you get your first perfect setup. I still fight with mine too.
Congratulations on the jump to RBA's and good luck. Lean on this site while you learn, we all do.