Im just wondering if the following will work, and allow the app to properly update on peoples' phones:
Sorry if I dont know how to explain myself, im just wondering if i do the above process will android/google see it as a NEW app or a proper update to an existing app. The reason I'm wondering is phonegap build seems to assign an 'App ID' and I'm not sure if this is just a phonegap thing or somehow gets passed on to google/android.
As long as the app id is the same, the version numbering properly incremented, and the signing keys the same, the Play Store will see it as an update.
For the app id, this is some you define in the config.xml file, along with a lot of other information about your app. For help authoring a config.xml file, you can try my ConfiGAP tool.