The 5.5" pads will suffice, the only difference between those and the 4" pads (other than size

) is the amount of time needed for correction. The larger the pad on the PC, the longer it'll take for correction / swirl remover. Many have used 7.5" pads with a PC (including myself) and can remove plenty of swirls with a PC, it'll just take a little longer.
As for the polishes, it really depends on the specific products. If they can be used by a machine you should be fine ... however the results may not be as spectacular. The final appearance of the vehicle mainly comes from polishing, so it's not a good idea to skimp in that department.