A:
Gas Gas Chasis -
http://www.gasgasmotos.es/en/manuals/search-250-f.html (2012 model but think its mostly the same chasis etc).
Yamaha Engine -
http://www.yamahaownershandbook.com.au/index.php (search the model)
B:
You mean the breather from the valve cover? On older models they ran down the front of the engine and sat by the frame rails. Problem was they would suck water in if hitting the starter when submerged. 2005+ they ran it across the upper frame to the airbox. Also it shouldn't be dripping oil. If it is it sounds like you have over filled the engine.