I recently just got rid of one of these after using it for more than two years - they are great machines, especially when you add in the SSD (I acquired the iMac in my signature and wanted to travel a bit lighter, so I "sold out" and got a less upgradeable Mac for portable use).
I've had good luck with the Samsung 840 Evo drives, although I'd recommend the 850 Evo now (better performance and the pricing is a bit better than the 840 Evo). I ran an 840 Evo in my computer's hard drive bay with no trouble for over a year and we've gotten them as inexpensive upgrades for many of the '09-'10 MacBook Pros still in use at work. They hit the sweet spot of good price, good enough performance for most users, and a good enough warranty. That being said, I heard a lot of good things about Crucial's drives and thought I'd try that this time around in my iMac (an mx100) - it's a bit slower for writes than my Evo was, but about the same for reads. I tend to prefer the SSDs where the manufacturer designs everything, as opposed to the idea of a controller and some chips that are mixed from various other vendors.
As far as cloning goes, I like
SuperDuper, just because the free version is good enough for most users to use once or twice, and it's a simple, but powerful tool. You can clone to your new SSD (after it's partitioned through Disk Utility, of course), using any generic USB->SATA adapter. This way, you can make sure the drive is ready to go before you start opening up your computer and moving things.
Finally, you can use the iFixit instructions to
remove your old hard drive, remove your optical drive, and then use a product like the
OWC Data Doubler to
mount the hard drive in the optical bay. Replacing items in the optical bay is a bit harder than the hard drive bay, but as long as you follow the instructions and are careful, you should be fine. The only scary parts are the small cables that connect to the logic board that are in the way and routing the wifi antenna cables.
The friend who ended up with my old one wants to do this or dual SSDs as well as boost the RAM even more for a nice, compact desktop replacement - I'm excited to see it get used to its full potential.