if you want a really good deal try printing out the offer and take it to Lowes and see if they will beat it or match it. They sell the PC but for some reason it has a different model number but it's the same as the 7424.
You'll need a flexible backing plate and at least one finishing pad and one polishing pad. Really bad swirls need a cutting pad.
Best to buy a kit from autogeek.net or detailcity.com or danase.com, there are many sites.
As far as screwing up your paint the greatest PERMANENT danger is dropping it on the car and denting. ALWAYS hold the pc with both hands using the handle.
You can swirl up you paint plenty good with the pc if you are using the wrong pad and product and not using proper technique. But the mistakes can be cured without having to repaint the car. The PC is an orbital buffer and not a rotary like the Metabo which can seriously burn a hole in your clear coat and base layer if you don't know what you are doing. The orbital or oscillating action of the PC makes it safe but slow.
an excellent site for a new pc user, has video of proper pc technique
http://www.paintcare-n-detailing.com/