Jason, Almost every hardware store around will have the stove bolts and nuts in their machine screws etc... section. They usually have a "stove bolts" section.
As far as the refractory goes, yours doesn't look all that bad. I would not try to chip it all off.
My suggestion would be, clean up the sides by chipping off any of those fused chunks or edges poking out. Then you can take your refractory "clay", grab a handful off the block and knead it a bit (if needed;-)) then push it onto any low areas and tap with a rubber mallet. All you want to do is fill in any areas that need material and/or smooth those sides out. Your goal is have as smooth a surface as possible so the ash drops when shaking. I even used a ball peen hammer for the smaller areas. Keep a damp sponge nearby and sort of wipe the area when you've got it looking good. That will smooth it even more so. You don't need it to be really thick either, that will just take coal space away. You are right, it is a bit of pain on this style stove do to the space constraints and that is why I suggest doing it this way. Might be easier with the barrel off the base too? I never did one on this type. My Glenwood pot was a seperate piece. If you can't get at it then maybe the pourable type suggested with a sonotube will work better?
As regards to the burner plate, Go to Tomahawk Foundry or Auburn stove foundry and they will copy the steel on in cast iron for you. Just make it like exactly what you want to finished one to be. http://auburnstovefoundry.com/
and give them a phone call.
Keep the questions coming and we can help with anything you need.