Did the tooth need a post? If there wasn't enough natural tooth or a problem with it due to decay or fracture, your dentist may want to put in a post, but he should tell you why. If he feels the gum would impinge on the crown edge, they at times will remove some.
Again, you should ask your dentist why he feels this is necessary (it may be) before you have anything done. Not all crowns are simple ones.
Actually it's not really that bad. The bone itself has no real pain sensation. Once the nerve is gone in the tooth, surgical trauma and swelling from the novocaine itself is the only pain cause, not the post placement itself.
I had four implants done and was amazed that they didn't have any pain at all. I felt nothing when the implants were drilled right into the bone at all. Pain after from an implant wasn't that bad either. Your root canal shouldn't be too bad. When you get home be sure to ice it. Try rice in a thin sock that has been in the freezer a couple of hours.
As for your gums, it might be worse if the crown top impinges on them and keeps them in an irritated state. Any procedure that removes gum tissue will be irritated and painful (like a pizza burn) for a few days though.
Warm salt rinses where you just hold the water in your mouth and then let it fall out, will help.
Let us know how you do.
My best to you,
Well, the thing about any medical specialty is that they want to practice 100% of their craft. A cosmetic dentist is going to try and give you the tops and very best in cosmetic looks. Perhaps that's not as important to you as it is to him. You have to explain that to him if that is the case.
If you don't trust your dentist, you might want to go elsewhere. It sounds like good dentistry to me, though. I've had several crowns put in where some laser work was needed for the crown to seat properly, and it didn't hurt at all, even the very next day.