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you have more than enough camera, 18MP you can get XXL on Fotolia and IS, you just need some lighting equipment and perhaps a nice tripod if you are going to do studio studio (objects, food, etc..)

I got a D90 and a cheap tripod (really cheap one not going to even talk about it eheh) you just need to focus on photography, shooting weak, better, whatever, shoot!

I use mainly a cheap 50mm nikkor lens

Some people will tell you its about the Camera other will say its about the image. I've stuck with one rule for over 20 years, buy what you can afford then learn how to use it.

As above, but what gear you buy depends on what you want to shoot. I think you get what you what you need NOW and are careful about what you add as you develop. I'm not as bad as many for buying stuff, but I've bought stuff highly recommended by others that I never use. I've also bought stuff I thought I'd use for new things I thought I'd like to photograph, then didn't follow it up, or got bored very quickly.
If you've got the money, fine; but you can also do fine with basic good enough equipment.
I changed that because some very 'basic' equipment can get you into trouble with artifacting etc.

Again, if primes work for what you like to do, why not?
A prime is one of these things people said I really 'ought' to have, but I never use.

I have a 100mm prime and I love it, but the lens I shoot with the most is a 28-135mm Canon.

I think some people can shoot great pictures with a low- to mid-end camera and equipment, if they know how to use it properly and light properly, and I think some people who can afford the most expensive gear out there need to take a few lessons. So I agree with the statement "buy what you can afford and then learn how to use it."

Great replies from everyone! This makes me feel great and confident now with some future considerations on my next equipment. My approval rates are very good with the Middle Tier (70%o to 92%) but once I hit the Top Tier my approval rates really fall fast (Fotolia 70%, Dreamstime 50%, Shutter 40%) due to higher standards in both composition and technical quality. 

I have about $10k in gear, the amount of gear I've bought, found I didnt use or like and then sold again if phenomal.
At one point I had 2 bodies and 12 lenses , now I have sony a900, 16-35mm, 24-70mm, 100mm macro, 70-400mm. I'm thinking about a 70-200 again , but I've been thinking about it for more than year and now I expect what I buy to see a lot if use and value. Some gear does make things quicker / faster / easier - L-brackets, vertical grips etc etc really nice when you've got spare cash and built up over time, but isn't essential and is often the stuff that you personally have to try and decide if you like or not.

Lost my tripod and RRS head last year replaced with triopo $179 tripod and head from linkdelight, expected crap but it was what I could afford in a hurry. The head doesnt 'feel' as nice as the RRS, but with RRS brackets it's actually doing a * fine job (as good as the $900+ combo I lost) and I now dont see a need to replace it (well not in a hurry , the RRS head was really nice - and I think there's the point for plenty of gear for me, nice to use, I hate the feel of the grip on Sigma lens feels like a powertools so i dont use them, regardless of optics (I know others do like it).

For all gear that I've bought some of my favourite shots and still best selling photos were taken with 6mp pentax and 2 lenses I bought from a pawn shop for about $25-$35 each

If you need it, buy it.  I have over $40K in photographic equipment; use every piece of it most every week.  All my camera bodies are middle tier (Nikon D300s and D7000); I owned a D3s once but sold it as it did not get enough use.  My most expensive piece of equipment is my 600mm f4 lens but I use it almost every day.

The good thing about quality equipment; you know it is your fault when a picture sucks!