Networking Advice, Hardware Help: (2) MbPro, TC, Airport Extreme, ATV

Hello,
I am looking for some guidance and recommendations on the best networking solution for my needs.

Brief Overview: Currently living in an apartment complex (lots of networks around me...my computer picks up over 10 networks from my apartment which makes me think high interference).

Current Apple hardware owned and used:
1. Early 2011 MbPro 15" (primary) (8 GB RAM, 2.3 i7, 750 GB HD)
2. Mid 2008 MbPro 15" (right before the unibody upgrade)
3. Apple TV
4. iPhone 4
5. iPad 2
6. Early gen 500 GB Time Capsule
7. HP AirPrinter

I use the 2011 MbPro running OSX Lion as my primary computer. The 2008 MbPro is currently reformatted with Snow Leopard.

I have noticed that the network performance in my apartment is quite poor, to say the least. Distance is not an issue as the TC is centrally located and is not more than 20-30 linear feet from any one location in the apartment. I have difficulty streaming any type of media from my devices to my apple TV, and I find that downloading movies (i.e. rentals from apple) can take an extremely long time (overnight in some cases). I use all of this equipment at my parents house, equipped with an airport extreme, and have no problems.

One of my goals is to greatly improve the speed of my wireless network (new TC vs. airport extreme with attached external HD?) I know this is an age old question that has been discussed many times, but I am not sure which might be better for this application. I am leaning towards the airport extreme as I would be able to purchase a thunderbolt external HD (when they are available) and take it with me if need be (I travel a lot).

My other goal is to have 1 central location with all of my media and files that I can access from anywhere (even remotely). This is where I was thinking of turning my older MbPro into a server (potentially using OSX Lion Server?). Anyone have any experience with this? As it stands right now, I cannot stream a movie that I have on my TC HD to my ATV (as this is not linked to iTunes library, but merely acting as pure storage). With an external HD connected to the airport and a server, couldn't I treat that external HD as not only a backup HD but also an external HD mounted to the server?

In summary, my desire is to use my old MbPro as a server to allow remote file/media access as well as enable streaming to ATV and to/from other devices (iPad etc) locally or remotely. Does anyone have any experience setting up a home network like this? Basically, a "home base" for all media files etc that can be accessed from any device.

I have other individuals that are regularly in my apartment and I would like to grant them access to be able to access certain files (but not necessarily all, such as sensitive works files). I am guessing OSX lion server will help me do this?

Thanks all for your advice and guidance. I am willing to invest some money to accomplish these goals, if need be. (new router/HD possible, Mac OSX Lion server).