Almost all old features will be supported in new version(so you can use Mobile App v.1.6 with your Dolphin 7.0.9), but some new features from Mobile App v.1.6 will not work on Dolphin 7.0.9 and will require Dolphin 7.1 (for example search page builder).

All this info is already updated in the documentation:
http://www.boonex.com/trac/dolphin/wiki/DolModMobile
But it still can be changed a little until the official release.