Actually I didn't have any Fireblocking issues - in fact it didn't cost me anything either as I used drywall that was removed as part of demolition.
The drywall taping/mudding isn't by any means hard - its just painfully slow as on corners you can only do one side at a time and need 24hrs to dry.
The area I had most problem with was trying to get the paper tape to bed in the mud. No matter what I did it kept bubbling. I found a tape adhesive which really helped me a lot.
In this pic you can see an outside corner with the left side with just tape glued to the wall (the spray adhesive is red) and the right side with 1st coat of mud.
This picture shows final mud coat with some rough dry sanding before I wet sand with sponge.
Hoping tomorrow is last day of mudding - and just sanding/sponging left