1.1 -> I suppose it is normal as this happens even if Polylang is de-activated and Types creates native WordPress custom fields. You can always hide the custom fields metabox.
1.2 -> You can keep the version as is. It will not interfere with the automatic update process.
3. -> I made basic some tests and did not run into any issues with custom fields synchronization together with Types. Did you check the relevant option in Polylang settings?
Thank you for your help proposal. What I most need is testing and bug reports when I make development versions available. You can subscribe to the Polylang blog to know when I release development versions.