Even if Lois did know 100% that Clark was Superman (which is debatable considering she apparently never noticed during the first movie-- and don't try to tell me she was too distracted), jumping out the window of a tall office building is still a wacky and idiotic thing to do. Especially for a grown woman and professional reporter.
Except we're talking about Lois Lane here. Fearless to the point of life-threatening recklessness is one of her defining character traits.
And the fact that she didn't see the resemblance until she saw it is perfectly believable. Human perception works that way all the time. You can be aware of something for weeks or years before you suddenly notice something about it, and then once you realize it, it becomes obvious and you wonder how you ever could've missed it. And really, given the track record of Lois Lanes (Loises Lane? Loes Lane?) in general, it's impressive that this one saw through the glasses at all.
And the idea of Superman being fooled by blanks in Lois's gun is just ridiculous. His response as Clark should have been to flinch and then say "Ha ha, very funny trying to shoot me with blanks". Which would leave Lois with no proof of anything.
True, that is hard to believe, but the scene is so well-played, even in the rehearsal footage, that I can live with it. If you like, you can borrow the premise of the Lester version that Superman subconsciously wanted to be found out.
Then again, screen adaptations of Superman have often showed his supersenses differently than the comics. In the comics and prose, he can be constantly aware of every sensory input for hundreds of miles around, but in film and TV, he's often shown as being unaware of things until he chooses to concentrate his senses on them. Which makes sense in a way. Both Smallville
and Man of Steel
showed us Clark being overwhelmed by his supersenses and having to train himself to tune everything out except what he chose to focus on. So maybe he was too surprised or upset by Lois pointing a gun at him to take the time to concentrate his x-ray or telescopic vision on the gun chambers and discern whether the cartridges had live rounds. And maybe he genuinely wouldn't feel being hit by a bullet because he's invulnerable and impervious to pain.