In order to get the plain 7424 PC to accept all the different pads that most people use here, you'll need a 5" or 6" diameter velcro backing plate of the proper shaft type at the minimum. I suggest 5" personally. Meguiar's and CMA sell one, and some other companies/places can sell them too although they can be 6" like the PC brand one. Also highly recommended is to get a 6" counterweight from a local PC service center or CMA or Coastal - this reduces the vibes.
Meguiar's, CMA, TOL, etc etc. all sell pads.
At the minimum, it's usually a good idea to have on hand one milder polish like SMR/#9, and one stronger one (next step up) like DACP/Fine Cut/PI-III just in case you need it. By default, try the milder product first of course.
HTH
