plaster cornice and polyurethane panelling: preparation?

[sunama]

Hi,

I have installed onto newly plastered walls/ceiling:
1. plaster cornice
2. polyurethane (plastic-type) panelling on the ceiling.

I have almost finished putting them both up and filling on the gaps.
I am now about to start painting the ceiling/walls.

My question
I shall be using Dulux Trade Supermatt (diluted 30%) to first prime the walls and ceiling. However, should I use the same paint to prime the cornice and panelling or do I have to use PVA solution or similar, first?

The panelling on the ceiling has its mitres filled in with coving adhesive/filler and the corners feel a little fragile, ie. if i take a screwdriver I can easily start scraping away and damaging the corners that were finished with the filler. Surely I cannot paint the panelling while it is in this condition? It needs to be stronger, this is why I was thinking about using a coat of PVA solution, first.

Thanks.

 

[Third_Eye]

Any chance of a few pics ?

 

[sunama]

A pic of the cornice that is installed.
Its quite large.
It has a 220mm projection, 150mm height.

Here is a pic of the panelling in the middle of the room, incomplete - I still need to do some work on it.

Here is the same panelling, in its earlier stages, however, the pic was taken in better lighting and with a wider pan, so you can see it better here.

If I take a scrwedriver to the corners of the panelling, it can chip and fall apart quite easily. I finished the corners using decorators caulk. Is there anyway I can strengthen it - perhaps by brushing pva solution on it? Or, do I simply treat the panelling and cornice as I would the ceiling and paint it (mist coat, then 2 coats of 90% Dulux Matt Paint)?