The IBM M1015 is very well renowned here and is about $100 to $150 on ebay so it's pretty much the same price so only your needs will do the difference ;)
Yes, they are called SFF-8087 breakout cable ;)
"6 HDDs can survive any 2 HDD failures" this is wrong. The redundancy is a function of the RAID-Z type, not the number of drives. For maximum redundancy you need to pick RAID-Z3.
Please re-read cyberjock's guide, read the ZFS article on wikipedia, etc.