If your planning to get into mining and buy more miners like a number of 6 you should atleast know your future cost of electric bills you will get in monthly form. If you planning to get sollar it much better to do it and buy sollar panels.
I See you got a good suggestions from a pro, so heres mine that I would say basic stuff to know.
GPUs
You are mentioning Ethermine and Nanopool, so I guess you will mine Ethash (ETC or ETH) or may Equihash (Zcash). You are using 2 X RX 580 8GB if you decide to mine Ethash coins such ETH, ETC and so on, for a better result, you need to modify your bios cards (You can find a thread about bios modding in this forum, simply just use the search function).
OS
You should choose OS that you think more friendly to you.
Pooled or Solo
If you plan to mine major coin, do pooled mining, don't do a solo mining except you have to plan to mine newly coins.
Wallet Address
Would be better using your own wallet (safer). But if you plan to trade it in the market, exchanger wallet address is okay, it would reduce a withdrawal fee from your mining poll.
Mining Software
For client software, I suggest using Claymore.
1. Make sure you have a nice area which is not in a hot place in your home.
2. Put the miners on the place where the heat is not always stays.
3. Why not try farm mining. Its also good to invest in a mining farm and rent a vacant space.