Figured I'd chime in and see if I can offer some words of advice. I second what and earlier response said. Get a new backing plate and some new pads. (Sonus,Meg's,Excel all have great products) I recommend you pick up at least one or two of the "polishing pads" and at least one of the finishing pads from whichever vendor you go with.
In looking at your posting you said that the vehicle is from 1991. My guess would be that such old paint will probably require you to step up a bit from the cleaning ability of
AIO and go with a slightly stronger polish such as #80 or #83 from
Meg's or one of the
Sonus SFX polishes. I would recommend that you start with the #80, make one of two slow passes with it and then check your work. If you are happy with the results, follow up with a LSP or pure polish. If you still have swirls, then maybe try something slightly more agressive on the scale.
AIO, from what I have heard is an awesome product and is a staple in most all detailers supply cabinets (Although I have yet to try it believe it or not) The limitation to it is that on old or neglected paint, it does have it's limits.
Remember as well that the PC is an awesome tool for your arsenal, but just be aware of it's limitations. On some really neglected paint you may not be able to achieve "perfection" but you can improve appearance %100.
Lastly, so far as the white pad that comes with the PC.... I found that a great use for it is to do the windshield. I use it to work in the Autoglym or Sonus glass polishes.
Hopefully some of this is of assistance to you.
