b. There is suppose to be difference. I don't know how much there's truth in this, but it's all over Internet, that even though optical bay is suppose to be SATA3, it doesn't really work with SATA3 speed.
I just changed disks in my late2011 15" MBP, and I put ssd in hdd slot, while I moved old 750GB HDD to optical bay. Both drives are recognized as SATA3, but ssd connects at 6Gbps, while hdd in optibay connects at 3Gbps.
3Gbps (sata2) is perfectly fine for hdd since it's reaching somewhere up to 130MB/s write/read speed, but 3Gbps would be limiting ssd drives (my ssd is getting, in real life, somewhere up to 480MB/s, which is more then 3Gbps).
I also heard lot of horror stories about hdd in optibay, but for now, everything looks fine on mine.
c. just as precaution I always de-activate Photoshop, when doing reinstallations. Maybe it's not necessary, but I still prefer to stay on safe side, then bugging with Adobe support if something would go wrong, and my license would be hanging on some previous, long gone installation of my laptop.