Speaker Wire Questions

[EQ3282]

Planning on getting this to wire the system:

http://www.monoprice.com/products/pr...mat=4#feedback

1 - Planning on wiring a 5.1 system around a 12x15 foot room (speaker in each corner, plus center and sub). Will have to go over two door frames. Think 300 feet will do it? Too much/too little?

2 - The spot for the right rear is tough. The couch is all that seperates living room from dining room. Planning to run wire under couch, but needs to cross walking path to get to sitting spot. Anyone know of any issue with cutting a small hole in carpet and running wire UNDER carpet to exit point at shelf spot? If this is 'not recommended' I will have to wire around entire dining room, which will add another 50 feet, at least, to the wire needed.

3 - Just to confirm, 12 AWG is good, correct?

Thanks.