In particular I want to know about the following Preview features which are already turned on by default.
Use GUID data types instead of strings How does this interact with Blank() and with Patch using a Blank() id to create a new record? How do I convert a guid to text for output?
Control property optimization What does this actually do? I haven't yet noticed changes in the number of properties of controls. Does it not affect the side visible by the developer of the PowerApps?
I also want to know about this experimental feature, which I have not seen take any effect yet, Formula-level error management It sounds very interesting, because I have had PowerApps, and apparently, the "regular formula checker" break down rather often after one minute change but PowerApps only pointing to problems in some other spot that was affected but not my last change that broke it in the first place.