After a lot more reading of both technical reviews and users' opinions, i'm starting to have doubts about my lens choice. I'm considering 2 cheap but good lenses, the 35/2 IS and the 85/1.8. Since DoF will be larger, will i have a higher chance of accurate focus on a 6D?
Get a 5D III. I see your case on this forum quite often. 6D sounds great from the begining due to lower price tag. Once the camera is in your hand and crappy AF becomes crappy, then you wish I have purchased 5D III. Keep in mind, 5D III has DUAL-CROSS type in center, therefore, it helps a lot with large prime(50L, 85L II).
Same thing for those bought 24-105, they thought the lens is "good enough" until they hand on 24-70 II.
Get better gear if you can afford it. It will save you a lot of time and money in the long run.
Here are some photos 85L II + 5D III, jpegs straight from camera, zero PP: http://albums.phanfare.com/isolated/oerWLRdp/1/6253867
In term of lenses, 85L II is an EXCELLENT lens for portrait. There is no other 85mm out there can really out perform 85L II @ $2000ish. If you want fast AF with decent bokeh, then get 135L.