3ds or obj is absolutely no problem!
Yes, I suck at texturing ^^ But I am willing to try!
If you dont want to post it here, you can e-mail me the texture at email@example.com
I started messing around with the models yesterday and it became clear that I havent modelled in a while, but I'll be on my feet in a couple of days.
And btw. if you want the sphere-shaped parts of the turrets actually sphere-shaped, it's going to be a problem keeping them to a 200 polycount.
I don't know how detailed you want them, I'll do two or three different models with different LOD so you can choose.
One with 150 - 200 polys and a 200-400 poly one.