Basic kit you'll need a soft pad, medium pad and hard pad, or a combination of each.

You'll really need to try a few different brands and see what A)works for you and, B) works well with the products you prefer.

Different brands have different versions of pad hardness, but they all give a cut rating usually. The DA's are less aggressive than a rotary so you can use a harder pad OR polish to get results quicker.

Once you get a feel for it you'll learn what products work and what pads you like. If you're doing a lot of different cars you'll learn how the paint reacts and what product/pad combo's are happier with certain paints.

Sonus polishes are good too. Have a look on detailing world forum and pick up some of the basics til you've got a feel for it.

Best tip i can offer is the triangle method. Start speed one, do one or two light passes (roughly just the weight of the machine) to spread the polish evenly, roll to speed two and do 2 to 4 heavier passes then up to 3 with a bit more pressure again for around 3 passes, then to 4 for a couple passes with a bit more pressure and you should see the polish start to go clearer, once it looks fairly clear, almost like buttery on the panel roll back down the stages of speed and pressure and do maybe 3 or so passes at 2 for a good haze free finish.

Once you've done it a couple times you'll get a good feel for it and wont need to think half as much about it.