I would stick with the E71 for email and calendar to be honest. I have the N810 and and N78 combo and even though the n78 doesn't have a qwerty I still use it for email more than my N810 This is because Modest the default mail client in Diablo will crash your N810 desktop whenever you set it to sync automatically.

If you really want to use a calendar I would use the GPE calendar and sync with google using erminig. There is plenty of information on how to do that on the forum.

I would also suggest a bluetooth keyboard for typing notes. I use the full version of open office writer on my tablet to take notes and can actually take notes and at the same time use the maemo recorder to record meetings.

Liqbase is a great little toy for scratching memos with a stylus, it starts extremely quickly which is awesome.