I might be wrong here but I think that all UPVC is white with a coloured film applied if required.
(kinda makes sense…. I can’t image upvc manufacturers producing all the colourways available) We renovated a little house and installed grey windows from a fairly big trade supplier – the grey was a wrap and they supplied a touch up pot to fix scratches.
If this is the case take care with your blue door as the white may show through if it’s scratched.
The fitter is saying to order two lengths of textured trim (we’ve 60mm at head to bridge)
Got to ask…. why didn’t you get a door/frame made to fit the opening?
Re the sealant, I think I’d go with the dark grey….. no-one looks at the top of the door frame anyway!