The simplest improvement that comes to mind is stop publishing to the cloud and develop on your local machine. That should cut your deployment time in half. Obviously you won't have your cloud database, but as most of your problems seem to be custom widget related it doesn't really matter whether the app functions correctly or not, you just want to see if it's crashing and/or throwing console errors.
A lot of your steps can be avoided when using the Mendix Developer App, which is available in the App Store of your mobile platform, see here (and ignore Weinre stuff).
Dexx's suggestion will probably save the most time, but if that isn't enough you can also look into building cordova/phonegap locally. A simple tutorial combined with unpacking the buildpack you get from the publish step in our cloud should get you pretty far.
Note that you only need to rebuild the cordova/phonegap package if you actually change stuff there! If you change anything in your model, you only have to restart or redeploy the model to the cloud.