did you scroll down the list of aircraft or click the FIGHTERS button to show only fighters?
The 190's fuel gauge is below your line of sight, you have to press keypad8+keypad0 to forward+down to see it.
Dive brakes are not modeled on the P38 yet, however I believe they are hoping to get them in version 1.03
For the brakes on the Hawg lower you gear. You can drop the gear at 350mph (just dinnae pull high Gs with them down)