.bsp format (maps)

1) There are many different .bsp file formats, you cannot reliably infer the exact format by extension alone, that said, Binary Space Partitioning is a space partitioning method originally used to increase rendering efficiency (depth tests used to be very expensive), but now is mostly used for collision detection. More information here and here

2) Depends on the format, Quake 3 BSP files already contain polygon information, so you should look up the spec and write a loader for it, if you're using raw text .map files, you will notice that there is no polygon information, each brush (convex chunk of geometry) is described as a collection of planes, so you must create a huge quad per each plane in the brush (coplanar with the plane) and clip it away using the remaining planes in order to get the actual polygon you'll feed to OpenGL.

Thanks, I'll take a look at those sites :D

Maybe also take a look at this and follow the link to a similar resource.