My 1st HT setup (HELP CRACKINHEDZ!!)

[PS3+HDDVD OWNER]

Well, despite it being Christmas time as well as the fiance's birthday i've decided to take the plunge into Home Theater. I grabbed an Onkyo TX-SR605 from my local CC right as they were going out of business, and i scored a pretty good deal at $199.99. Also that day, i picked up a Polk CS2 center channel speaker for $63 !! Yesterday, i order a pair of Polk Monitor 50's off of CC's website, and they are due at my front door anywhere between 1/5-1/9. This gives me a little time to plan out what kind of speakers i will use as my rears, as well as select a decent starter subwoofer. Also i will need suggestions on speaker wire, banana plugs, etc. Lots of planning involved here, haha.

I'm wanting to stay with Polk for the rears, and i'm debating between Monitor 40's (Black) or just order another pair of Monitor 50's. This setup will start off as a 5.1 setup and expand when i replenish my secret savings account

As far as a subwoofer, i eventually plan on going with the eD A2-300 which 99% of the board members here swear by. However, funds are running low as i stated earlier b/c Christmas is right around the corner and Xmas day happens to also be my fiance's birthday

Can anyone suggest a good entry level subwoofer, possibly in the $150 range? If not, i'm likely just going to say screw it and order the damn eD subwoofer

Also, i plan on bi-amping my setup since it will start out as a 5.1 setup. Is this a good idea to get the most out of what i will have? Will that be too much juice running to my modest Monitor 50's? Any suggestions you guys can share on this subject?

And as far as cables are involved, can someone point me in the right direction here? Will 12 guage do? I'm going to need a good 100 feet, as my room is about 18' x 13' and i'd like to have some extra. Help a noob out guys!!