I've been running OpenElec XBMC with RPi for quite some time now.

IceFilm, 1Ch are good but recently i m using SimplyPlaer and GoTV/I wanna watch to watch US TV Series in HD. Especially SimplyPlayer is highly recommended.

There's no simple answer to which repo to use. U can go to XBMCHUB.com forum to read up on all the available repos but for me easiest way is to install all the REPOs and then install all the add-ons 1-by-1 to try them out.

There is also a wizard in FUSION which will install the most common/recommended plugins for you. Go try them out

Good Chinese/HK/Korean sources are scarce nowadays. Mainly using Azdrama.net , Good Drama and Drama Crazy. Last time AzDrama used to have lots of 720p sources but noawdays 240/480 at best

KissAnime is great, they stream 1080p animes and all up to date

For sports you can try Navi-x or SportsDevil (maxmusterman Repo)

But nowadays HD sports channel are also hard to come by sigh...

To me RPi is fast enough. All depending on the SD Card you use. Also i moved the storage to USB ThumbDrive instead of SD Card itself and the best thing is you can easily Overclock RPi to make it faster (I m using medium settting).

Try to google as much as you can, all info are there. Once you get a hang of it, it's easy.

i've even managed to reprogram the buttons on my TV remote for one touch functions like searching for Subtitles etc