Help with best wired/wireless setup

My house has been wired for Ethernet. In my basement the ethernet cables that go to the various rooms are connected to the comcast router. My idea was to have a router on each level. I'd like to use ethernet for most things but wifi for iphones and ipads. Right now I have my time capsule in the middle floor and the extreme on the top floor. The problem is, the idevices don't jump from router to router. Is that even possible?

If you set up the roaming network correctly.. ie same name wireless, same security setting and password as per the standard roaming network instructions.

http://support.apple.com/kb/ht4260

Then some devices can hop towers nicely (Macbooks generally ok).. whereas iphones and ipads do not jump towers so well. (thinking of wifi like the 3G signal when you are out and about). The technology to jump from one wireless to another is established but some cards and drivers don't work as well as they should. If that is the case you have no choice but to manually switch off wireless and switch back on again.

Otherwise your layout is the best practice. Apple recommends roaming over wireless extend. And most wireless gurus do as it is far superior method.

Lastly, in my basement, I have 1 ethernet port but 4 devices I want to connect to that port. How can I accomplish this? A switch?

Yes, buy a switch. Let me recommend you actually buy a switch with enough ports for everything and have just one ethernet to the comcast router. So buy 8 port gigabit.. that should be enough.. if not then even a 16port. Using a single switch is the best way as it means all the devices are tied together with the best efficiency. Gigabit 8 port switch is a consumer item.. any big computer store will have them for $50 and pretty much any brand is just as good. Buy the Linksys or Netgear if you want longer warranty.