Yes, you can
http://www.amazon.com/s/ref=nb_sb_ss_i_4_7?url=search-alias%3Dcomputers&field-keywords=2.5+to+3.5+hard+drive+adapter&sprefix=2.5+to+3.5+hard+drive+adapter%2Ccomputers%2C230
I would really suggest getting both SSD for OS, and 1TB HDD for the games and data, if you can afford it of course, but you can buy that second disk in a month or two after buying the whole system
Is there any point getting higher stats than 12.8 for gaming? I think not, cause what game needs to put 12.8 GB/s, this stats is more fur editing videos and rendering, correct?