hi? i just bought a 2000 suburban lt with 185k miles.

since i just bought the vehicle, i notice that when i start it the brake pedal jumps or kicks up.

what am i suppose to do to prepare this vehicle last me for a long time?

and what am i suppose to do to get better gas mileage?

and what mods am i to do to increase performance?

what am i suppose to look for?

what is your advice for me?

the center console. at the back of it, it has RAC plug in inputs what are they for?