IOS – How to sync all Gmail with iPod touch

Depends what calendar you're adding the events to. In the Calendar app, in the top left, there is a Calendars button which lists all the calendars on the phone. You should hopefully see your MobileMe calendars in there, labelled as such in their own section. The theory goes that you should see any events on MobileMe that you've added to the calendars listed under the MobileMe section of the screen.

I would guess you're adding the events on the iPod touch to the wrong calendar, but it could be there's a separate issue. You'll need to check what Calendar is selected on the Event screen when you're adding or editing the event.

There's a difference between syncing with iTunes and over the air sync.

If you set up your Gmail account to use over the air sync then when you open up the Notes app (on the iPod), you should notice a back button on the top left that allows you to change which account you use for notes. If you choose your Gmail account and start creating notes, you will start seeing them appear in your Gmail account, under the "Notes" label. This sync happens automatically once you press the "done" button on each note (as long as you have an internet connection).

This has nothing to do with iTunes sync.

You will only see notes that you create under this account in Gmail. You will not see all of your old notes. For that, see this question.