Chromecast - tab-casting and laptop - help.

So I have a Chromecast which I am very happy with. I am also in the market to finally upgrade my Dell lappie which I have had since the beginning of 2008.

The situation is that I also have a NAS filled with HD videos and music which I would like to stream to my TV connected to a home theater setup (complete with receiver, amp, speakers and wires). I do have an HTPC (Windows 7) with XBMC which I use to stream my movies to the TV. As you can imagine my living room is full of wires and that is getting really old. Plus, while I am satisfied with the HTPC setup, if there is a way to be cleaner via Chromecast, I would like to explore it.

Enter - tabcasting. My old lapppie definitely cannot handle that load. It can hardly play 1080p videos straight from my NAS. But other than this relatively heavy load of tab-casting HD videos, I won't really be using my lappie for anything heavier than browsing/editing a few MS Office files. My other must haves are a long battery life (6-7 hours+), reasonably light. Would really prefer a 13 inch but willing to go to 15 inch. And a reasonably good user experience. It would be nice if it were powerful enough for me to browse while tab-casting an HD video. And future proof. I like to use my lappies 4+ years.

So Apple just announced the 15 inch Macbook Pro with the Haswell i7 for $1200. It sounds about perfect for me but I have never owned an Apple product (not even an iPod). Was never willing to pay the Apple premium through my educational years, but now that I have some saved up, I don't mind paying a little extra for the better experience. I have also been out of researching for laptops and am finding wading through the myriad of Windows PCs a little soul crushing. Haven't used Windows 8 but so far can't find anyone who seems to like it.

Hoping you wonderful people can help me out just a little bit.