This all sounds very fun! But hey I'm a huge geek Cool

I've accomplished all of that but using the DIR-615.

Black spots are a huge pain in the a*se, like you said just run a cable to another Access point (AP) that will cover the black spot. You could look at powerline adapters if you didn't want to run cables here there and everywhere. I'll link a few at the bottom. They run your network through, effectively, you home power cables. It's rather awesome!

If you were to run a cable or powerline to a new AP. I would recommend doing this next to your PS3 and then using a port on the new AP for your PS3 connection.

NAS is very easy to setup, Synology are very reliable and easy to use. I think thats your best bet, just hook it up to your main router and config the settings and your off.

Before you go buying anything, check out the Slingboxes, I'll link it below. Excellent TV streaming system!

Powerline // http://www.amazon.co.uk/TP-Link-PA411KIT-AV500-Powerline-Adapter/dp/B0084Y9N3O/ref=sr_1_1?ie=UTF8&qid=1366543918&sr=8-1&keywords=powerline+adaptors+triple

Slingbox // http://uk.slingbox.com/