I used the Tamron 28-75 f2.8 for awhile moving from D90 to D600 with it. Great lens and currently for sale ;-)
Great lens for the price. Really. I upgraded to the 24-70 for the wider end and VC. I also have the Tamron 70-200 non-vc and get great results with it. Plenty sharp for me and picked it up for ~$550. Little slow to focus and no VC but I get by lol.
The 35mm 1.8 will work in Crop mode. The D600 will recognize it and start acting like a crop sensor cmaera.
So effictively it will be the 50mm you already have. Dump the 35mm and reinvest it.
How much are you selling for?
I am a little disappointed now. This change over is going to get pricey but I guess that's the choice I need to take to get better.
Not trying to solicit my business but this is where I am currently on my work. www.danddphotos.com
(if mods have a problem with me linking that I will gladly remove)
So my understanding now is I need a $400 35mm if I want prime? haha
As for the 70-200 tamron, I am considering that but thinking I should just stay with the 70-300 till I have enough for the Nikon 70-200 as I know its just that much sharper and nicer of a lens. (could be wrong) How slow is the actual focus? I hear about it but never sure who knows enough about photography.