I print my shots on A4 (well 8" x 12") and they look fine... they come from a Canon 30D which means in megapixels a 8.2 MP camera.  My prints are around the 4000 x 2600 mark, including a photoshopped frame and to be quite honest they look stunning (ie doubt anyone could tell they were digitial instead of film) - and i doubt there would be much problem with an A3 print of the shots i have on higest quality - but as always if you invest more you get more. The higher mp you go in the DSLR standings the better your image is going to get in terms of being able to print them and sell them.

In terms of lenses - well, investing in the best lenses out there is going to give you the best images... it all boils down to your budget, because in terms of lenses there is a decreasing return on investment on lenses - ie the increase in performance isnt directly related to the price - you pay say 4x more for a lens that is 2x better than the one below it....  Take that into consideration when choosing your equipment...

"In every colour, there's the light.
In every stone sleeps a crystal.
Remember the Shaman, when he used to say:
Man is the dream of the Dolphin"

Rich Meadows Photography