[ArdentZeal]

1. I am using datetime (enddate or "how long in your list"), vicinity, opening times, shared users and parent to childtask hierarchy at the moment.

And yes you are absolutely right, that there are several factors which determine importancy. So as I am not yet able to reading my users' minds (Im working on it, believe me :)) the result will never be 100% accurate. But I think it is already good enough to be of valuable help and it will only get better from here.

2. There are frameworks out there which you can use, but as the sync is mission critical to my app I do not like to be dependent on any framework. So I rolled my own sync solution, based on Nodejs with a postgresdb in the back :)