1.   Seal all wall joints with joint compound and tape.

2.   Then cover the filler wood with a thin layer of joint compound and paper joint-compound tape.

3.   And, it takes great skill to apply this joint compound smoothly enough to avoid sanding.

4.   Any joint compound you may smear on the wood bead can be washed off with a wet sponge.

5.   Apply joint compound twice more.

6.   As for the joint compound, the proof is in the pudding, and I must assume that the bucket contains ready-mixed compound, not powder.

7.   Attach the tank to the bowl using joint compound on the nuts and bolts to ensure a tight seal.

8.   Be sure to put in three layers of joint compound, and smooth off after each layer dries.

9.   A. The corners are splitting because no tape was inserted in them when the plasterboard was installed and joint compound applied to finish the job.

10.   A. Filling the craters with a thin layer of joint compound might work, but I would be concerned about its peeling, just as the paint did.