Who delved deeper?

[Frandîr]

So, this might be a not so difficult issue to resolve but I have been thinking on how the Dwarves of Moria delved so much into the earth that they ended up disturbing a Balrog.

Many questions arise:

Was Angband deeper than Moria?
How did the Balrog got there?
How long was it there?
Did it was part of any of the mayor events in the First and Second Age?
Did Sauron knew this Balrog was there?

Just some itches that I would like to consult with fellow living creatures through this medium, and not rely on spurious cleverness from the mechanical hearts.