How long should each part for the Personality section be..?
How long is a piece of string? There's no good answer to a question like this; it is, however, important to split your time in the most efficient way.
The personality section is worth 25 marks. 10 marks are allocated to Part A, and 15 to Part B. So, you should be spending about 18 minutes on Part A, and 27 minutes on Part B! I personally recommend spending LESS time on Part A (aim for a max of 15 minutes), and longer on Part B (the harder section).
Again, there's no 'answer' to how many pages you should be writing. Your writing may be gargantuan, or miniscule, you may be a 'quality' or a 'quantity' person, or a mix of the two. If you get out a couple of pages, you'll definitely be in a good position to get a great mark