The N900 is an amazing handheld computer, and I'm sure it's possible for somebody who knows what they're doing. The question is, how do I become someone who knows what they're doing :-)

It requires .. Lard.
Copious amounts of Lard.
and not the cheap stuff.

actually ...its more fun when NOT knowing what one is doing...

just jump in to using it.
google what you need or are curious to know.
ask questions here.
follow the wiki...
stay in the shallow end of the pool until you feel comfy with stuff that can mess up your device. (so avoid for the present stuff that isn't stable..)

It is pretty much what everyone else here has done ..to get familiar with the n900

Also if you use a good old fashioned debian distro ...then it will feel similar in structure, since the n900 is debian based essentially...
So the normal stuff won't seem so daunting ...
So I would suggest becoming familiar with pc debian distros to help with your learning curve on the n900..

As far as the Logitech F310 + USB Hostmode..
Hm.
I have no idea if it will recognize that game controller...
I would suggest using the search tools here and in google