Good point on the whitespace- will take a look.
As for creating tasks- we're thinking of a sticky area on the left (that's always on) to create tasks.
For priority- we're releasing labels in 3 weeks. You should be able to assign #P1 or priority overall on different sets of tasks. That being said- we are considering adding some form of auto recognition or NLP to suggest priority and labels automatically based on past tasks. For time, we have 3 effort options (points, hours or days), we kept it simple to create a standup view where you can see how engineers track throughout the week.
Let us know which other parts may be tedious. We have more work to do!