You are right that it will be lots better when they start going outside
and yes cats do like a clean tray
We have 7 cats and 4 trays hardly any of which get any use any more but I scoop poop as soon as I see it. Indoors or in garden.
If you feed good quality (high meat content) food they shouldn't need quite so much of it and should therefore poo less frequently. If you are going to change food though, should be done gradually to try and avoid tummy upsets.
We had a cat called Dingle many years ago and she could knock you down at 30 paces
No such thing as Internet then for advice on feeding. I remember being so embarrassed picking her up from the cattery after a holiday once