You'll really just have to play around with her diet to figure out what works best for her. It could be adjusting the feeding times by an hour or two so that the difference is a little bit closer to equal, it may be cutting out some food.
When I got Saphi, I originally tried for the two meals a day about twelve hours apart, give or take. She wasn't eating her 'breakfast' -given to her sometime between 7 and 11- until 6pm or later, so then of course she's not eating her supper till at least midnight, if not later. I'd eventually just cut her down to one meal, in the evenings (tried mornings, she wasn't eating till evening anyhow) and that's what we've since stuck with. She very rarely eats when I'm not home, doesn't eat till after I've gone to bed if it's just her regular kibble and water (wet she'll eat sooner more often than not), so her daily meal is consumed between midnight and two am basically.
The increase in water intake is likely as a result of the change in food (increase in protein), it's a good thing as long as she's not having issues with peeing or anything.
RE Kibble removes plaque: this is highly based in myth. It's like saying eating croutons will help remove plaque from your teeth - would you believe somebody that told you such? And keep in mind that -with appropriately sized food at least- cats generally don't chew their kibble too much, so really, if only one in every five pieces is actually being crunched, how much is it helping?
The best thing for teeth is to regularly feed raw meaty bones (poultry (chicken, duck, quail, turkey) wings and necks and such, whole prey rodents, etc.. for cats), and/or to brush their teeth.