what's about the analog ports and the DAC's-Out
You could add attenuation/amplification I suppose with some opamps, I'd probably be inclined not to but maybe.
Ti has some Bidirection Levelshifter with 8 Ports or else
Yes, I'd use the TXB010x series.
there must be enough place for all IC's
I would say there's plenty of room.
I know a lot of people have talked about this but I'm not convinced it's worth it. Possibly for legacy projects that are currently working but just need a it more grunt with the new processor board.
For anything new I'd work with 3v3 and if necessary level shift just the few signals you need to.
Rob