oki... perhaps i should make a models overveiw might stop questions of this nature.
models ploygons depend on how often they appear, how many appear, the rest of the worlds count, blah blah...
basically model however you want - just use some common sense, obviously you can't have 120,000 polygon cars with 1024x1024 textures as that'll slow on any graphics card.
best to keep textures to 256x256 (which all standard 3d cards handle) and models in a reasonable polygon range. As Milkshape starts to seriously lag when you hit 2,000 (3,500 on GeForce4!!) i don't think count is gonna be an issue.
the shape looks pretty good, and the texture has a good start, but i would finish the mesh before starting the texture - it saves alot of time later.
Anata aru kowagaru no watashi!