There is minimal API 8 required which is Android 2.2 and there is no maximum, so all future versions should be compatible, also I've tested on Android 4.2 emulator - it runs on it. Please provide more info and error messages (with screenshot please), so we can investigate it.

Yes, new 1.7 version is backward compatible and can connect to Dolphin 7.0.9 sites. However some features may be turned off, like Facebook login.