I do not play or run DnD 3.5, but if you want a feel for how combat is run, you could go to the Games section of the site, and search for 3.5 games that are under way. Peruse some of them, seeing the tricks and tools each DM uses, and that should give you a good base and feel for how things are usually done. (:
I'd also like to say that maps are more important in PbP than they would be on tabletop. Without quick and immediate dialogue between players and the DM you can easily get into misunderstandings that can bog down the game and frustrate everybody (what do you mean I'm too far away? I said I was moving to the side of the room before I fired. You didn't say the room was 100' wide! And so on).
Maps don't need to be fancy, a simple text graphic is fine (tip: use courier new as a font, the width of each symbol is the same). Personally I'm a fan of maptool.