Actually, this build looks great, I see you have done your research. To answer your questions:
1. Looks like you have found a solid build already.
2. Since you have a Z68, yes. I would suggest getting an OCZ Vertex 3 60GB for your OS and highly used applications (SSD cache) and say a 1-2TB HDD as back up.
3. A single 570 will be plenty. But also, make sure you leave room in the future for SLI and other capabilities.
4. If you are doing a lot of extensive memory use (Video/Graphic editing) stay with the 16GB RAM. But honestly, if you don't use the applications on a daily basis using extensive amounts of time to make and edit material, drop to 8GB.
I would honestly go with what you like. The TT Armor case gives you plenty of room for added features in the future. Yes 10 drive bays is a lot, you will probably never use them, but it never hurts to have then right? Plus, if it is a front loaded HDD bay, be careful, because a lot of cases get cut off in the middle bays (have to remove the trays) for large video cards.
And one last thing! I didn't see a CPU cooler. Are you planning to overclock? If so go with one of these:
Newegg.com - Noctua NH-D14 120mm & 140mm SSO CPU Cooler
If that is out of your budget range, go for this:
CM Hyper 212 EVO:
Newegg.com - COOLER MASTER Hyper 212 EVO RR-212E-20PK-R1 Continuous Direct Contact 120mm Sleeve CPU Cooler Compatible with latest Intel 1366/1155 and AMD FM1/AM3+