1. Which is best mining software needed in windows 10 for mining ETH? I know its going to be POS soon, may be I'll mine until then.
the best depends on users taste, hashrates are not a big differences, some prefer a low fee or free, some prefer for a user friendly miners
2. I have two RX580 but from different manufacturers. Does that matter? Do I need to install gpu drivers for both the GPU's?
no, brand doesn't matter, what matter is the model and memory types, Samsung, hynix, Elpidas for modding
3. Which Wallets are you guys using to receive the mined coins rewards? Suggest something safe and secure. I have in mind is Jaxx and Trust or Myether wallet.
I use mew for longer Hodl, and respectable coin exchange wallet for fiat conversion to pay cost
4. Suggest some good Altcoins that could be mined using RX580 graphics cards.
Whattomine.com
Cryptunit.com