Under the hood on the drivers side near the passanger compartment
trans worn out, get a newer taranny Try running the trouble codes before making exspensive repairs. It may be mass air flow sensor
Take it to auto zone and hav3 the codes read for free.
Lug bolts are normally hammered or drawn into place with the use of the wheel. They are removed the same. Remove the wheel, you may have to set the rotor in such a position that allows for the lug removal. Usually a very small gap allows for it. Take a good hammer and carefully pound it in till it pops out the back. Take your new one and push it in than tap it a few times till enough thread is showing that it can be drawn in all the way with the wheel installed.
Before you dive in and replace the computer, make sure that the computer actually needs to be replaced. More often than a defective computer the problem is a defective sensor or a bad connector plug or wire somewhere. On a 14 year old car be careful about replacing an expensive item like the computer.