Hi Unclued.
I thought 10 was quite difficult also. I was trying for some time to find the actual name of an artist (?UIT). But when I had only 2 or 3 letters of the playwright left to find, and one of them had to be an 'I', I realised that 10 is not a name, but a general term for a painter belonging to a certain school. 4-letter bird.
The 2nd A is an anagram of octave.
Yes, the final grid has 4 empty cells.