I took stock fans off and using external Arctic USB stick fan. Way more quiet. Can run up to 744 no problem. My main issue is finding a USB HUB that can handle watts required. I've come to the conclusion that anything under $75 is not going to cut it if you want to run 10 ML2 above stock.

As to your other questions. You pool or solo mine as long as they are scrypt algorithm based coins.

LOL, I hope you didn't buy these thinking you were going to make a profit. If you do, it'll take a long time. Whatever hardware investments you made with ML2, cooling, hubs, etc. Then if you pay for power instead of stealing it, you have to factor in that cost.

I do it more for fun and learning how to mine than actually thinking this will make me money.