Some game physics map related questions

Ive been playing a little over a week, and have become familiar with 2forts map. I play mostly pyro and demo, and now I have some questions, to answer confusing details, that I really cannot discern in the heat of battle:

The grate- You know, at the choke point where the two front door entrances goes to one hallway, with a grate & murderhole [technical term] in the roof:
- do flamethrower flames damage enemies through the grate?
- will stickybombs stuck to the undersides' blast damage carry over to the top side of the grate, or vice versa?

The courtyard:- with the catwalk around its edges:
- same questions: will flames wash up over the edge to hurt things from below?
- stickybombs underneath: damage guys on top?

Doorframes/corners
If a stickybomb is set off when its stuck to a corner, does the blast damage only stay on the side of the corner that it is most on, or is the blast all encompasing? Put another way: do door lips offer blast blind spots?

Thanks for setting me straigh on this sorta stuff, so I'll know one way or another if its worth even thinking about.

The grate -  very simply, "no" and "no," neither go through the grate.

The courtyard.
The flamethrower will go through the stairs from below.  It will go through from above based on your positioning, if you're aiming at a stair, it will deflect off instead.
Stickies cannot be trusted to deal splash damage from below, but it is possible of a straight line can be drawn from the bomb through the stairs to a victim.

Again, theres a bit of gray area with corners, since stickies can damage in both directions if set on a corner.  However, a bit of splash radius will be cut from the wall to which the sticky is not directly attached.