+1
In addition to the sandpaper, get a set of polishing cloths with 3200, 3600, 4000, 6000, 8000 and 12000 grits. They're what a lot of people around here use. Then go to the polishing compounds. I use Novus 1, 2 and 3.
I never use anything mechanical when polishing paint. I have enough trouble polishing through paint on corners using my fingers. I'd really mess something up using a power tool.
One thing I've learned since I've been back in this hobby, there are very few shortcuts. Some things just take time, patience and control. Hard for me to do sometimes.