Welcome to Gransnet Grannytwoshoes, I had elderly cats sadly all gone now, but my vet told me a variety of reasons why mine were 'very vocal' in old age, could be deafness, senility and thyroid related problems, one had hyperthyroidism and she drove me bonkers with yowling in the middle of the night. But bless them all I loved them to bits and the last two beautiful kitties lived to 21 and 20 so reached a ripe old age.. I never found a solution to the problem we had to learn to live with it..
Mine would also rather drink from a dirty puddle in the garden than a bowl of nice clean tap water so no idea why they do that apart from the fact cats like to do as they please and thats apparently what pleases them... I've loved all my cats but can't say its not a relief now to be able to holiday or go out for the day and not have to worry about them.