Just a note, endscene is called twice, once by the steam overlay, once by MW2 itself.
Check if the call was made from inside MW2 and not from inside SteamGameOverlay.dll and you should be able to draw just fine.
I do not use S0b's Overlay hook, I am coding a D3D "Overlay", Just talk to me on MSN and I will explain more precisely the thing.
Yes, By editing XP Manually. The Level dropdown thing just uses defines I added, And modifies your XP with the correct ammount, I didn't felt adding 70 Dropdown choices, Lawl, So, Try to get a Level / XP List, Or work by trying.