Its not a stupid question in the least.  Make sure you understand ahead of time that the tan is the finish that is most prone to chips/ scratches with thermal cure finishes.  If you decide to get it, make sure that it is not being applied over a finish which is teflon, as it will chip/ scratch much easier.

If you don't mind having your tan lower look worn after awhile, its an option that many dealers can help you with.  I only bring this up because people are often looking for coated receivers to look pristine, and that isn't really what happens with the tan.  On a brighter note, its not like it just falls off, but it does wear quicker than the OD Green and other colors.

No, the Stag lowers are not teflon coated, and I would strongly recommend that you do the refinishing work yourself.  

The color matches are pretty close, but not exact.  I've coated plenty of plastics, but the tan colors seem close enough where I wouldn't even bother.  

The stock is coated with Norrells in these pics.  The other parts are factory tan.