Wasn't the Hood undergoing a refit on the Clyde when she set out to sea? I believe that a number of shipyard works were still onboard when she went in to battle and they were lost along with the crew when she went down.
The Hood was fatally hit in less than 10 minutes of the commencement of the battle and went down in 3 minutes. Given the extensive explosions on the Hood that caused her rapid sinking its likely that many of the crew were probably killed as a result of them although many would still have drowned
no, PoW still had small number of civilian workers onboard (she'd not long been commissioned and was having a few turret issues)
Hood was (over)due a refit, but it had been cancelled again when war was declared (because Hood, Renown & Repulse were the only 3 ships fast enough to safely stomp all over a pocket battleships or the twins)