What kind of stats are you looking to collect? Defold has its own analytics features which can collect some basic usage stats.
There are various analytics services which support HTTP APIs which you could implement. Depending on what you want it could be easy to setup something. I have not tested it yet, but you could try using the PlayFab analytics features https://api.playfab.com/playstream/docs PlayFab API Implementation https://www.youtube.com/watch?v=9hmZp5ND4D8
It’s possible the upcoming extension system will allow us non-Defold devs to implement things like Flurry support natively.
The minimum iOS version is listed as 5.1.1 in the default Info.plist. It’s possible the actual minimum is higher as they might have not updated that as features which require more features were implemented, don’t know.