1979 tarm mb-30 convert to coal

I was lucky and my great aunt gave me this boiler. 1979 mb-30 It was full of creosote and the water coil is leaking but the rest seems sound.
Question #1 should I leave the old coil in it and cap off the ends. instead of trying to pull the doors off to get at it.
#2 I ordered one of two last coal kits from tarm just in case i want to burn coal. Is coal a good Idea in this boiler any tips?
#3 I want this as a sub to my oil boiler and the garage is not always heated can i still use the temovar valve?