I have enough channels on my Wii now that they have spilled over to a second page. It's very cumbersome to have to move to that second page to access those channels when there are other channels on the first page that I use very infrequently. Can I move the channels around, or am I stuck with their current layout?
Yes, press "A" and "B" to "pinch" the channel, and you can move it wherever you want (except for the Disc Channel).
As well as reordering the channels you can move them to an SD card. The Wii will take up to an 8GB SD card for this, but some games that save content to SD cards won't recognise such a large card. Check each game for the maximum size card it supports.
Some will even run from the SD card, but others have to be copied back to the Wii to be run.