Aurora-R4, upgrading gpu questions.

i have an alienware aurora r4 im going to be upgrading soon and have a few questions. 

Current Specs are:

16 gb ram -- intel i7-3820 @3.6 GHz -- GTX 680 -- Nothing has been upgraded, bought from alienware so im assuming it came w/ the 875W PSU. 

I finially am going to be upgrading the gpu to a GTX 10' series. and was wondering what i should consider, skipping so many gens. i know ill have to do a BIOS upgrade, currently have A07. Can i go strait to the newest from A07 or should i upgrade them sequentially? Also if anyone has any experience with issues in dropping a 10 series in a r4, i know the case is pretty small for newer cards, and some cards are hard to fit in the case, with overheating issues and such. don't plan to SLI so i didn't think fitting would be an issue, but i'd  hate to buy it and see that it doesn't fit. thanks in advance.