The Autopia package includes all that you need, but I would buy a couple of extra pads (at least one or two extra greens and maybe an extra blue) to go with it.
Or you can order a good set of pads and backing plate from Excel Detail. Start with the Pad/Plate kit for $29.99:
http://www.prestostore.com/cgi-bin/store.pl?ref=exceldetail&ct=&pd=97914&pg=14145
Then add something like two green pads (polishing), a yellow pad (med cut), and an orange (light cut/polishing) pad. All seven pads and backing plate will only run about $60, but youâ€â„¢ll have a nice range of pads to use and an extra one of the most used pads if you switch to a different product during a detail. Between the kit and the extra pads you'll have:
1- Yellow Medium Cutting pad
1- Orange (light cut/polish) pad
2- Green polish pads
2- Blue Light Polishing pads
1- Gray finishing pads
1- 5" Backing Plate
You can adjust the number of pads depending of the products you're going to use, but you won't beat $60 for a pad kit like that!
I wouldn't use the TW rubbing compound at all (sandpaper in a jar), and would be careful with the polishing compound too. A good starting polish combo would be Poorboy's SSR2.5 and SSR1, or Meg's #83 and #80:
http://www.premiumautocare.com/posuswre.html
http://www.premiumautocare.com/meguiars.html
If the Ryobi is just a small single speed random orbit unit that I'm thinking it is, then you'll get much better results with a PC. The Ryobi can not be used to polish out defects like a PC can, about all it is good for is applying wax. You'll love a PC and with the right pads you'll be able to do a lot more, and do it faster.