Mazda Miata 1992 questions?

[Sebastian]

Helllo everyone, I have a few doubts regarding my mazda miata 1992, I hope someone is able to help me out. Well, ever since my dad purchased the vehicle many years ago, when we fill the tank, there is a sharp smell of gasoline that will be on and off until the needle indicating how much gas is in the tank is right about at the middle, then it wont smell anyone. Also, it seems like, although I dont know if this is just an illusion, that when full, the first half tank lasts 100 miles, and the second half tank 50 miles, to complete a 150 miles per tank, note I live in Costa Rica so the terrain here is much more difficult than driving in nice straight highways in Florida. A few days ago, I accidentally hit a speed bump a little bit roughly, but not too much, and the red airbag light turned on, ever since, its been coming on and off every once in a while, may it be some loose wiring, or an actual problem? Also, everytime I use the car, even if its for 5 minutes or for hours, it quickly heats up until the needle marks the middle of the heating marker on the dashboard, is it normal that even in 5 minutes of usage the car quickly heats until the needle marks at the middle? It also doesnt matter if its using coolant or water. Until date, there has been no problem with that, but it does get me worried, because now I just used it 10 minutes, and when I opened the hood you can feel the intense heat, but this has been always and never been a problem, even for extended use. Do some of you have similar problems, is this normal or not? Any tips? Thanks guys any insights appreciated!! Note, despite all that, I LOVE the miata, its had minor failures in YEARS of usage, its an excellent car, even in rougher terrain not meant for this sort of vehicle.