Completely New to This - Need some help

Please forgive me for my noob-ness. I decided to build a mining rig for ETH and other cryptocurrencies, so I've done some extensive research on google. However, I have some questions left unanswered by the "how-to guides".

Question:
1) In some guides, it says I have to sync the currency's blockchain before I mine. The quick start guide on this forum and the Nanopool help section doesn't have this, so which is correct? Or is it implied the blockchain is sync-ed?

2) I got most of the hardware including 4x Rx580s. I was hoping to dual-mine with the Claymore miner, since the increased electricity usage is offset by the secondary coin. Again, do I have to sync the blockchain of the secondary coin as well before I mine?

3) If I do indeed have to sync the blockchain, is it possible to use "Parity Ethereum" to fast sync? Or should I go with the geth method?

4) I have some unused HDDs sitting around, can I use those instead of a SSD?

5) If I do get the mining rig up and running, should I ever let it cool down once in a while? Or should I just let it run 24/7? There is alot of info on building the rig and such, but very little info on maintenance.

Thank you for your help!