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...a lot of people see some rust and go overkill, so without photos of how bad yours is, it's difficult to judge whether bead blasting and replacement of the paint is the preferred option. But if you do go with this, find a powdercoating business that has some experience already with bike frames.

Mark or mask out all the problematic areas like BB threads, crown race seat, fork threads, etc. Then expect to do some cleaning up of these areas when the PC gets baked onto them anyway. In general my biggest problems here in doing a couple of rust bucket bikes with powder coat have been in those areas.

There's one bike listed on the local CL right now, a Raleigh SBDU frame, that is ridiculously cheap because when it got powdercoated, the coater bead blasted the interior surfaces of the head tube so much it no longer holds the headset races firmly without shimming.

A lot of PC colors are pretty glossy.......which some people like, others think looks too "plasticky". There are some options for a less glossy finish, which you might want to ask about if it's a concern.