Scamp,
Welcome to the forum. You will find a wealth of knowledge here, and folks are friendly and willing to help you out.
That said, let's get into your questions.
1. ABC from Auto International will take off old wax, synthetic coatings, and any rail dust/industrial fallout/acid rain that may be in your paint. ABC is concentrated, so follow the directions on the bottles. I have used ABC twice now, and was pleased with the results. ABC took off any old wax/Klasse I had, and just left me with a nice, clean finish.
2. Clay Bar. Clay is nice to remove any embedded contaminants that ABC did not remove. I would say for a really nice finish, use the ABC, and then clay.
Be sure to read the forum's tips on using clay. Mother's Clay, Pinnacle Clay, and 3M clay all seem to work well for folks on the forum. One thing, you don't need much pressure, let the clay and the lubricant do the work. For lubricant, use what comes with the clay. Otherwise you can use Eagle One WET quick detailer as a great lubricant for claying.
I assure you that the clay will really get your paint nice and smooth.
3. Swirl removers. Okay, so you have cleaned with ABC, clayed to remove additional contaminants and now you want to polish/swirl remove. 3M has some really nice products for swirl removal. I have used Meguiar's line for years, and I think 3M has a better product.
Now comes inspection time. How bad are your swirls? Can you feel the scratch/swirl with your fingernail, are they like small white lines? Or are they really light swirls which only the sun can show?
For medium to heavy swirls 3M sells a 3M Perfect It II rubbing compund in paste or liquid that is nice. I would say apply this by hand always.
Use a good quality terry applicator, and after ABC and Claying, work the 3M into the paint in one direction only for say about 15 to 20 strokes. Wipe off with a nice terry cloth or MF towel. Spray on some Rubbing alcohol(isoprophyl) and wipe off. Now drive the car out into the sun, or shine a light on it. Is the swirl gone/diminished? This way you know what you have done and your results before you continue. Also, only work a very small area, 2 x2 or less. This way you also make sure you are not adding more marrs to the paint surface than you are taking away.
For light swirls, 3M swirl remover for dark color cars is nice, using the same steps I described above. If you have a porter cable orbital buffer you can use 3M Perfect It III Machine Glaze, which is just a newer swirl remove for use with orbital/rotary polishers.
Whew, this is long, but you asked.
A final few words of caution.
1. Abrasives, like 3M rubbing compound should ONLY be used on metal painted surfaces. DO NOT use this compound on your front plastic painted bumper or rear plastic painted bumper.
2. Any abrasive, no matter how mild, can cause finer scratches. You will find that in using rubbing compounds you will have some fine scratches left over. That is why you will need both produts for severe swirls/scratches. One to remove the heavy stuff, and the 3M swirl mark remover to remove the fine scratches left by the rubbing compound.
3. Go slow, do small spots, take your time. This is very important. Removing swirls can be a breeze, but you need time. Just think of it this way, when you compound/swirl remove you are really applying a solution like liquid sandpaper(although it is milder). Don't rub in circles or back and forth. Use single direction strokes, and use medium pressure.
Others more experienced than me will give you info as well....so learn all you can, then proceed.
You can find 3M products at Trak Auto, Pep Boys, Autozone etc.
ABC can be ordered from autoint.com, and the clay can be found at the stores mentioned above.
SJ