I have been told by my dentist that my permanently crowned tooth needs a root canal. Can this crown be removed & re-applied after the RCT?

Most likely the Dr. that does the RC will drill through the crown. Then use a filling material to close the hole that was made. Its not uncommon at all.

I just had a crown legnthening procedure done because there was not enough bone to attach the crown to--DO NOT HAVE THIS PROCEDURE DONE!! IT IS BARBARIC AND my dentist acted like this wasn't going to be a big deal. IT IS HUGE--THEY REMOVE BONE WHICH WEAKENS THE REST OF YOUR MOUTH. My tooth is a canine so my smile is crooked now and feels very strange. I imagine this could also damage nerves in your face and bother your sinuses. Had I known what I know now I would have gotten an implant. Research your obtions and avoid this one if you can!!