You can create rain by using PaintFX, you'll see a weather folder in your visor, just choose rain and paint it in your viewport. To animate it go to the individual strokes and keyframe changes in them. You can do it with particles as well, just seems like a lot more work to me
To permanentely join two Nurbs objects, use the Nurb's Boolean Tool
Darkon
Red bellows of flame have blackened my stones
Convulsing my frame and cracking my bones
Hell's dragons of steel who roar in their chains
Crawl into my caves to suck out my veins.....
-The Mountain P.F.M.