Don't bother with flash unless you can throw around a lot of money for a bunch of speedlights or studio lights, stands, modifiers, wireless triggers, etc. It just isn't worth it.
Also, the SB-600 is doubly a bad choice due to it being expensive and its lack of a PC-sync.
I have an SB-28, and I barely ever use it. Sometimes I'll hook it up with an off-camera TTL cord for some harsh light, but I've done that like 10 times. I would use flash a lot more if I had a flash meter, stands, modifiers, and a bunch of (3+) speedlights or studio lights. Alas, I don't, and it doesn't really impact my photography that much because I do next to no studio work, and absolutely no commercial work.
Also, I would never get a 50mm lens...It is too long to be used for general purpose, and it is too short to get any tele shots. Personally, I treat my 35mm lens as a normal and I want to get a 28mm lens for wide. (My perfect outfit would be a 28/1.4, 85/1.4, and 110/2...but I'm not made of money.)
Just save your money. The lens is a waste, and so is the flash.