So many lovely questions. Where to start...
Firstly, Plague Bringer: I think it would be appropriate to ask a "Senior" mapper for help. Many mappers, good or bad, should ask questions. ANY one should ask questions for ANY thing. Also, there are no restrictions on to what md3/ase files you use. Hell, you could grab the hotdog cart md3 from Urban Terror if you felt like it. I want to see how you incorporate this in your map. Use the boxes, by all means.
Secondly, Survivor: Part of your question was answered above, so i don't need to repeat myself.
There is no max limit. This means someone who is an excellent modeller can transcend texturesetlimitation with mapping since everything is allowed in moddeling and actually only needs to add caulk and related trem entities.
Also why do there have to be models. The minimum limit is a mystery. Why minimum 2, what does it add?
I also see that without an upperlimit good modellers can easily overcome the greatest brushwork mapper because they are not limited within texturesets nor Radiant design limitations.
I'm not
entirely sure of what you mean by this, but if im right, you mean that you think people will make the entire map in a 3D program and then just pop in some other stuff in Radiant afterwards. This is fine. If anyone does this I will be very impressed.
Thirdly, TRaK: Very interesting point. Maybe I might give a list of shaders that you can use anytime.
And lastly, everyone disliking my texture limitations: ...
Go listen to rdizzle.
Thank you for you questions, and I apologize in advanced for this double post. I still need to get a messages across.