Can't I sort tasks by any criteria? Also can't add labels at time of creating task...
Sorting tasks is indeed not available in our Android app yet, but we'll add it in the future and you're welcome to vote for this request in our Votebox: http://todoist.com/Vote_Android/showProposal/31/
As for labels - it's also not available yet, but it will be soon in the upcoming updates.
When can we expect the sorting functionality to be added?
Also how abt seeing completed tasks in the Android app?
Also isn't sharing of tasks via email possible?
Unfortunately, we can't give you any timeframe for that. We're working on adding completed tasks view right now.
Sharing projects and delegating tasks will also be available soon after our big upcoming update, but now sharing via email, unless you're referring to allowing other people to email tasks to your projects - that's possible. For details, right-click on a project and choose "Email tasks to this project".
I m referring to sharing of tasks they the Android app, not the web app - not possible yet, right?
Unfortunately, that's indeed not possible right now in our mobile apps.