There are several recent threads here about expectations for the next PBs, which most assume will come out next month. There are also lots of PB vs. iBook threads; it'd probably be worth doing a search.
The 12" PB is apple's lightest, but it's really a fairly neglible difference compared to the 12" iBook. Both the PB and iBook can connect to your TV and play DVDs, but only the PB can connect to an external display with an all digital connection (DVI), which produces a sharper image. The iBook connects via an analog (VGA) output.
It sounds like the 12" PB with superdrive option best meets your needs, but it's worth waiting a few weeks if possible to see what the new releases bring; if nothing else, they'll make the current 12" PB cheaper when Apple sells them at a discount as "previous generation."