Yes, you can Compel or Invoke any Aspect you are aware of, it all works exactly the same.
No, just the limits of your Fate Point supply (and common sense in trying to preserve them).
You can limit it through the use of Scopes (sidebar on p53) if you're concerned about people trying to win by simply throwing FPs at conflicts.
Table rules, basically. By the rules both are perfectly fine, it takes mutual agreement for the player to use one rather than the other. If the player has described moving into a really tight space, then perhaps it can be Compelled for effect, whereas if its just more confined than the open, only for the penalty.
(Being Persistent, the player doesn't have to pay any FPs for this to happen, either).