How well is the online executed? Not very well at all in my opinion. There is no lobby, you can't talk to people or create games or join clans. You simply have a screen, you click a button, it connects you to a random person whom you don't speak to at all, you play them and then you never see that person again. It's not to different to playing a computer opponent really.

And most importantly, are friend codes game specific, or do they use my Wii Friend Code? Game specific.

I've not played it enough to answer the other questions.

As for Resident Evil 4, I wouldn't bother just yet. The controls are brilliant and its the best version yet. I have the Ps2 version but I bought it anyway. However, if you're a bit strapped for cash I'd say its best to put it off and buy some games that you have yet to experience.