The uvw unwrap for the glock does have quite a few pieces (especially compared to source models), but its not that bad really, there are worse.
If you want to start out simpler maybe try a grenade or knife first. For gun models, the sawedoff looks like one of the simpler ones, but I havent checked every one.
And just for the record; all Source games have pretty much the same directory structure. First you have the "main" game folder which invariably has the full name of the game (Counter-Strike Source, Left 4 Dead 2, etc). Inside the main game folder you will have engine related things and also a sub-folder whos name is an abbreviation of the game name (cstrike, l4d2, csgo etc). Its in that folder you'll have all your content, divided into maps, materials, models etc.
All model textures are found in the materials folder, not models. In fact, all textures are found in there, everything.
GCFs and VPKs will normally drop you straight in at the cstrike, l4d2 or csgo level.