Hopefully one of the more seasoned Blender guys in here will be able to answer some of you guys questions, but since I am just browsing, I'll give them a shot just from having read stuff in here.
@Hell-Fly4Ever
There are many ways to do this that I can think of, changing the texture itself, changing the smoothness or normal maps, or just removing those maps until you remake them to have a more appropriate level of reflections.
@BattleMetalChris
I think this was discussed earlier in the thread, I may be recalling incorrectly, but I kind of remember it technically being possible but not being supported by the exporter maybe.
@weiwei
This has been answered in various places, do a search for glass in the forums. You can use an alpha map for the non-opaque parts and adjust the alpha settings, but the end-result might partially depend on how picky you are with the blending between opaque and transparent I guess. You could also create a separate face(s) where the opaque parts need to be, and then assign your regular UV map to the faces that need to be opaque, but this of course depends on what you are doing. There are some good threads posted by others showing various results with glass, I am not going to post them all here, but they are easy to find.