Well, I can't help you with all your questions, but I may be able to answer a few. 
First, when on eBay, I always set it to "Buy it Now" and "Newly Listed" and then if there is a really good deal you can get it before others even see it!  Personally, I would try craigslist and garage sales near you (though it's pretty late in the year for garage sales).  Maybe put an ad in the paper or craigslist, "looking for LEGO" or something (but make it catchy).  I've had some good luck with asking nearly everyone I know if they have any LEGO they don't use anymore, especially high school graduates going off to collage, a lot of them keep their LEGO but when they move they just don't want it anymore. 

Rocao at brickset just said this the other day:

That seems about right for some stuff I've bought, but is usually harder to find online.

Maybe try a search more like this (scroll down about halfway and then you'll see more) if you're looking for it by the pound or a better feel for what people are selling LEGO lots for:

http://www.ebay.com/sch/i.html?LH_BIN=1 … mp;_sop=15

Also, look if they have things kind of sorted or not.  So many people say New Mint LEGO or All LEGO bricks or ONLY LEGO toys, etc. and a lot of the time I see things that aren't LEGO in their listings!  So (I know this probably isn't exactly what you're looking for, but who knows) if you see they care about LEGO it's probably better, like this:

http://www.ebay.com/itm/HUGE-LOT-OF-OVE … 3f1fa39799

Is way more likely to have only LEGO and good quality pieces than, say, this:

http://www.ebay.com/itm/Huge-LEGO-130-L … 4d076f3f28

With all the stuff in a big mess, just thrown in the bins, minifigs missing hands or drawn on, etc.

I'm not sure how helpful any of this is but I hope I've given you some basic ideas.
JonnDthunDer

Personal Website + Portfolio
Available for Film Composition

Almost invariably, "Buy it now" prices are way more than what typical people would pay.
I always sort my results by "ending soonest", the way ebay used to sort by default.  then you wont have to wait long.

I also suggest posting a listing in a local trade paper.  my ads usually go like this:
"Children all grown up?  I'll buy their bulk Lego bricks!"  You can find a lot of stuff at low prices.
Check out yard sales, too.  For $25 I bought the $150 X-Wing Fighter, a $50 Space Shuttle Set, lots of the smaller sets that were related, a bunch of X-Racers, an $80 technic dragster, and lots of misc stuff!!!!!!!!!!!!!!!!!!  The whole lot was worth about $450 to $500 retail.

I didn't see a link for your question posted but your third question I can try to help you with. The Friends sets have a lot going for them in the smaller ones. Mia's Bedroom (3939) has a drum set, bed, night stand, desk, flower pot, book, basket and light for 9.99. The bed looks like it can be made into a couch with the slopes as the back and a few pieces from your collection. And if you can find one in a Wal-Mart still they might be cheaper than advertised. The one here discounted them fairly recently.

I'm not sure if the color scheme would work for your project as the colors are vibrant pastels. You could always look at the set itself and get some ideas then make an order for bricks you need.

Jared