timing belt have to be removed to install the cam gears, however it is not necessary to replace the belt if the condition is still good and used below the manufacturer recommended mileage replacement. however, it is up to you whether if you want to change the timing belt while installing the cam gears, as you may save a little from workmanship fee later on.
you will not need to change the cam cover when using these arospeed cam gears. the size is the same with stock gears.