wow, very nice progress! This is starting to look like a real game now!! And thanks a lot for making it open source 
Looking good albs_br! 
Cool! Keep up the good work!!
Do you mean acceleration, progressive speed/camera movement, variable height jumps, skid when changing direction, etc? Yes I plan to make this. It's very important and really makes difference for a "professional" looking game.
I strongly disagree with that hehehe
Physics should go along with the gameplay. Inertia/acceleration/etc. are hurdles that the player needs to overcome to control the player. If you want to base your game mechanics around that (e.g., like in Mario), then that's fine. But not all games need nor should have that. Just imagine "1001 Spikes" with inertia... it'd be horrible I am not saying that you should not include inertia, but just that you should think of what is the gameplay that you want to have in your game, and implement the physics that go along with that
