1) There was a small radar in a tub between HACS directors - something T-shaped for our small scale is fine. Kit from Flyhawk leaves an empty platform without lantern- that is wrong, I see people do this on few builds.
The as-fitted drawings claim a pompom director, but nothing to see here. There is no radar there for the period you are building the model. Might be a UP sight (of which there is no info)
5) Walrus - green and grey colors, 2 Walrus planes (not 4! despite plans) were carried. Halves of its wings were stored on hangar so if modeling hangar open - good to add those on the side
I have a few of the IWM images at high res but I cannot make out any camo on the upper surface. There is a difference between upper/lower half of the plane, most notably visible on the engine cowling. But then IWM_A 4231 shows camo and a different roundel too.
What still remains unclear:
6) Motor Launches: were they blue with white bottom or all grey?
Complicated. Some pics some an all-grey 25 FMB (IWM_A 3868). (IWM_A 3900 & IWM_A 3898) suggest a blue + white 45 FMB. After the 45ft FMB were replaced by the 35 FMB it is mainly white upperworks. Images of KGV from the same period show some boats with a notably darker hull (and covered upperworks), sometimes same as hull colour (no white upeprworks). I cannot be very more helpful at the moment... I think I need more footage
7) Is it acceptable to cover all boats that were rowed with tarp? Is it acceptable to cover with tarp motor launches (various)?
Actually boats were typically covered but I think it's acceptable to not cover them... makes for a more interesting model.
Were decks painted grey or scrubbed clean for April-May 1941 period? Some photos show decks uniformly clean in Ravens book, same as turrets and it is the biggest argument not to leave them natural color.
Scrubbed.
9) Did the ship's crest got painted over in grey or was in white-red?
No idea!
10) Color of shafts on props - gold or steel or painted grey?
Never gold. Pics of her in drydock shows the same contrast as the hull colour; which makes sense as shafts were often painted with hull colour, so red.
11) name plaque on the stern - Prince of Wales - was it there? Was it there but painted? Was it removed?
The name on the hull was letters only on the stern during launch but covered during fitting out and afterwards (see e.g., IWM A 9409 with a strip where the name was during launch). Might have been covered? Never noticed this before...