Painting inside the hornplates

I will soon have to undercoat and paint the inner and outer surfaces of the Horn Plates.
1. Do you need to mask off around where stays on the boiler are screwed onto the horn plates ? (ie you will have a metal to metal contact)
2. Or do you just undercoat and paint the plates on all surfaces and then bolt them on?
3. I will probably paint the inner surfaces with black heat resistant paint.
4. I had a bit of a fight to assemble all the spokes on the front wheels .I had to play around gradually settling in all the spokes on the front hubs. Is this normal?
Before I start "aralditing" in the spokes I need to check that there is nothing unusual happening.
5. My engine arrived with the smokebox already fitted. How do you seal and tighten up the large brass hexagon plug in the boiler front tube plate?
Many thanks

Hi

From Building Crystal.

Hornplates inside where the mating surfaces. Thin single coat of paint. No problem with loosening in 3 years.
Spokes can be bit tricky as very precisely made especially at 2". Does your wheel run fairly true dry fitted? Couple mm run out will never be noticed.

The plugs all need ptfe tape on the threads before putting in. This will seal the threads and make steam tight. I use a socket with 2 off 12" extension bars.