Can I now uninstall/delete my green wallet app? to be less vulnerable to theft/hacking.
Not necessary but it's up to you. Kind of a hassle if you will install/uninstall it again for every session.
To lessen your worries if you decided not to uninstall the app, set up a security passcode. It should have that feature as it was common for any crypto wallet*. Then for additional security, set up an application lock which is a default feature of an Android phone nowadays.
I can still receive but not spent this way right? Should I create a couple of addresses beforehand
Make sure you have the correct address. Since you will uninstall the app, you don't have any references beforehand.
Honestly, I'm not aware of this wallet.
Are you really sure you want to use that one and not considering those recommended ones for Android e.g Mycelium, Electrum for Android etc.
