Thanks for the input.
For the first input: I would actually use apps in Podio for this. Check out t he article on when to use apps and when to use tasks, I think there are some interesting points in there.
Second input: you can press "T" on your keyboard anywhere in Podio to create a new task. It will automatically choose the item/app/workspace that you're looking at as the reference, but you can click "x" on that and then search where you'd like to attach it to. See screenshot below.
About labels, you can read a bit about what we think about them here: http://blog.podio.com/2011/06/10/podio-and-gtd/.
Hope that helps and thanks again for the input!