Hi prateek,
It's good that you have started communicating via mailing list. You can go for the above along with IRC.
Be patient enough and respect the mentor's time.
If there's any query regarding your project as specified go for the mailing list , than contacting the mentor via his mail. Because in here even other DD (Debian Dev) would also help you.
Regarding the project,
I hope you have gone through this [0] first and wait for the application tasks which are yet to be announced for this project, since we have 5 days for the official acceptance. Then all your queries on data to be used or UI/UX stuff would be cleared :)
Importantly, solve at least one before writing the proposal.
Hope to see you soon with some contributions.
with regards,
Kaushik Reddy.