For question 1:
Porting to iPod Touch 4G is not yet in progress because no one is porting to it yet (the guys doing the reverse engineering do not have iPod Touch 4G). If you have reverse engineering skills, you can help with the porting.
Or if you are lazy to port, you can donate
http://www.idroidproject.org/wiki/Donations for the devs to get an iPod Touch 4G.
Once porting is complete or partially complete, Android can run on iPod Touch 4G. But the timeframe for that cannot be said, it can be weeks, months, or years. Take in mind that porting to the current devices (iPhone 2G, 3G and iPod Touch 1G) took around 1-2 years before the current state we are in (with some features still incomplete).
For questions 2-3: I think there are a lot of themes and stuff found on the ModMYI repo/site. Of course, your iPod must be Jailbroken.