Yes, NiMH rechargeable batteries are a must for Wii gaming. I actually slightly prefer them to the built-in batteries on the Dual Shock 3 because you can just swap them out if they get run down, rather than trying to play with that dorky little USB cable plugged in. It's a rare issue for the PS3 controller to get completely drained if you plug it in whenever not in use, but it does happen, and it's annoying when it does. Maybe that's Sony's way of telling you to take a break already. 
You can try one of those 3rd party charge packs if you like, but I find brand-name rechargeable AA cells more trustworthy.
You're absolutely right about the shopping channel needing an overhaul. It's clumsy to navigate, and the progress bar was cute the first time, but desperately needs to be muted every time I've used it after that.
I actually prefer the Wii's channel-based interface, but I can see how some people might find it annoying to navigate.
MPT is a great choice and an incredible value. I also consider Mario Kart Wii an essential game. Of course, you don't need to buy and play all the great Wii games at once. 
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
