Well first things first, let me be the first one to welcome you to Autopia!
To answer your questions, I would first use a claybar to remove all contaminants from your paint. Then I would purchse some good polishes to remove those swirls before you apply any Zaino. I would recommend any polish that does not contain, fillers, lots of oils, or wax as they will interfere with the Zaino bonding. Some polishes that i use in conjunction with my Zaino would be Poorboys SSR2.5,
Menzerna Twins (intensive Polish and
Final Polish 2) THese are great polishes that will not interfere with your Zaino.
As far as applying Z with the PC, I would highly recommend it since i have better luck with it spreading Zaino thin and evenly. I would only use the Gray finishing pad (or any glaze applying pad). Just spritz the pad with a little Z6 (Lightly mist) to help the Z spread out. For myself, I always remove products by hand with a good quality Microfiber.
Take heed that the Z5 says it removes swirls, but in reality it doesnt do a good job, use polishes for that task.
Many members use traditional waxes after they polish because that polishing will offer no long term protection for your finish. Wax and sealants are kinda of two different things. (do a search for those topics as its discussed a numerous amount of times on this forum. ) Zaino is classified as a sealant, and therefore has no real polishing action.
Hope i have answered all of your questions, and again welcome to the board!!
Feel free to ask any additional questions about my response.
Chris