Hi Vivek,
This is interesting. I consulted with a colleague and this is what we recommend:
Yes, collaboration during development is done only by using a source control (in Web IDE only Git is supported). If you don't want to use a public Git server (as GitHub, Bitbucket, etc) you can use the HCP Git by deploying to HCP from Web IDE without activating, just to have a source control and check the checkbox in the deployment dialog to connect to a Git repository. Then manually push the changes from the Git pane.
From then on use Git to share the project's code from Web IDE.
When you want to deploy to your ABAP repository do this from Web IDE, and when developing a new version – work on the source code in webapp folder (again use Git to collaborate your code) and deploy again from Web IDE by using the 'update' option – so the same app can be updated and no new application in Fiori Launchpad should be created.
Never import and keep developing on that version - import is for reference only.
Regards,
Michal.