Hi TCC, I've got some excellent sources of info, I can recommend Peter Padfeild's book 'BATTLESHIP' and 'The Grand Fleet' by D.K. Brown.
Jellicoe was unaware of the practice of cordite handeling in the fleet, after Jutland a damming report detailing the magazine errors was written, but Jellice had it quashed and wrote his own version blaming lack of armour protection around the magazines instead!
It is probable that the ships captains knew of the practices but as to whether they instigated them or not, I do not know.
Both books go into great detail regarding development of British gunnery upto WW1, the amazing inovations and astonishing errors of judgment made. (example; Jellicoe was in charge of choosing which director system to fit to the fleet, one by a civillian Arthur Pollen, or his personal freind Fredrick Dreyer and chose the one made by Dreyer. Dreyers system was a poor copy of Pollens, it was unable to work under helm so the ship had to be steered in a straight line to be able to calculate the firing! But Drayer was a pal and his was cheaper, so...)
I am sure about the rangefinders, it was only just before the war started the the fleet extended the fighting range upto 10,000 yards, pror to that it was at about 4,000 yards!
The other factor involved would have been visability, in the north sea low vis is common and at Jutland the british rangefinders were at a disadvantage. British ships were clearly visable to the Germans but were obscured themselves. Mind you, the Germans over estimated the range too and fired well over Beattie initially but corrected much more quickly.
I am afraid that lack of armour protetion or cordite scattered aroud his mags would have been the last thing on Beatties mind, he just wanted to get stuck in!
All Battleships and battlecruisers have what is called a 'Zone Of Immunity' inside of which the trajectory of shells is too flat to stike the armoured deck and at too steep an angle to penetrate the side armour, Hood had just entered her 'Zone' at 20,000 yards when Holland made his turn to bring all guns to bear, Bismarck's shell(s) struck Hood near her mast (no-where near her main mags) and egnited the 4 inch mags or possably the above water torpedoes, a chain reaction almost instantly broke her back and blew the 15inch mags.