Like fillings. Now days root canals done by an experienced endodontist can be done in 1 visit microscopically. Only a very small numberof root canals cause any pain. Don't be fearful, it will go well.
Usually minimal pain. Most root canal treatments go well with little or no pain during or after the procedure. There are certainly exceptions to the rule, however, and unfortunately, these are usually what people talk and hear about. Fortunately, these exceptions truly are few and far between.
Talk to your dentist. I would refer you to a dentist. It's not my field.
Dental surgery. The dentist will use a numbing medication prior to doing the root canal, and then will prescribe pain medications for a few days to take after the procedure. Most people report moderate discomfort that resolves in 2-3 days on average.