Recently every time I brake for a long period of time, for instance at a red light, the brake goes all the way down to the floor. Then when I go to accelerate after, I barely touch the gas pedal and the car starts to quickly boost in speed, then goes back down to the speed where it should have been. Also the car's RPM gauge goes up even when I'm not touching the gas pedal. What's wrong? :(
Sounds like you have 2 problems.
Brake pedal that goes down to the floor at a red light is a bad Master Cylinder, replace it
Common issue as cars get higher mileage is the Thottle Body and throttle plate get gunked up, use an approved throttle body cleaner in a spray can to thoroughly clean the TB and idle air control valve and passage.
+1 on @Moab's answer about the master cylinder, that is a classic symptom of a bad master cylinder.
In regards to the revving when not on the gas, it sounds like your ECU is getting confused by something. If you have a check engine light on pull the codes and see if there is a component failing. Another thing to check for is a vacuum leak. If air is bypassing the MAF sensor at idle it could cause the engine speed to increase