MacOS – Syncing Notes with Gmail & iCloud

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.

With iCloud, you can choose which areas to sync and which not to. However, if you do choose to sync contacts and/or calendar, I believe you will simply end up with some double events on your phone, which can easily be cleared up by disabling view of the extra calendars.

In short, syncing contacts, calendar, music, and photos are all separate and can be enabled/disabled as such.

And yes, it does, in some way offer you additional redundancy as the Apple cloud and Google cloud are likely housed in different data centers...but this would require you to keep both calendars in sync, which I don't think will be easy to do without being annoyed absurdly.