1. Not sure, sorry
2. you can certainly watch some streams with the right add ons. Not sure about firstrowsports.
4. You can get a PVR version which will record TV for you, provided you have a TV card that is (this can be a bit fiddly though in my experience)
5. Depends if you mean the software or the hardware I guess. They update every now and again and it's always seemed fine for me. Hardware changes shouldn't affect things much as it's just running on the top of Windows/OSX/Linux anyway.
I've been using XBMC for a year or so now and I absolutely love it, though I use it mainly to play movies and TV shows I've ripped or otherwise acquired on a NAS. I started off running it on top of Windows 7 and then Windows 8, but as I don't use that PC for anything else I moved to OpenELEC, which is basically the Linux version of XBMC but with everything but the necessaries stripped out. If you don't want to use the computer for anything else I recommend this method as it's super easy (you don't really see or need to access the Linux bit of it because it boots straight into XBMC) and you don't have to spend ages stripping out Windows components you won't need that get in the way. The OpenELEC team are only a few days behind the main releases from what I can tell in terms of getting the updates out there (they integrate an autoupdate feature into their version as well).