First more then likely your front end is set with some toe out which most racer run between 1 and 2 degree tow out. So you center your trim where each wheel is pointed out the same.

I do not recommend putting your finger over the stinger to stop it unless you have gloves on, as a big block pipe gets HOT! Stop it buy either pinching the fuel line or tapping the flywheel through the chassis with your shoe. I use my finger but best to have a glove on.

You adjust the brakes but the brake rods. I do not have the RTR as I only do kits but if it is the same as my Pro kit you have to siliver knobs on the 2 brake rods and by truning them you make the rods shorter or longer. Keep in mind RTR radios and servos are barely adequate! All so some questions take days to get answered so have some patients.