Being realtively new to the Killi scene I would like to ask a few questions at this stage of my obsession

I have a few species that I've been harvesting eggs from. Once hatched I place the fry into a small plastic container (chinese take away containers) with java moss. The container is approx. 12cm diameter and the water depth is about 4cm deep. I feed them BBS as first foods. Is BBS ok to feed aphyosemions as a first food, the fry seem very tiny to me and I was wondering if green water or infusoria would be a better first food? Is it safe to use store bought products like liqui fry as first foods or does this muck up the water quality?

How often does one need to do a water change on these small fry holding containers (daily?). When is it safe to move them to a bigger grow out container?

How do you guys separate the various batches of fry? Lets say I harvest eggs today from one species, then 1 week or so later I again harvest eggs from the same batch. Do you now grow these out in separate containers or can they be combined ( I suppose smaller fry will become food for the bigger fry so using your own discretion would be best yes?).

Once the fry are grown out do you put some back into the original long term breeding tank or do you keep them separated from the parents? Do you start new breeding setups with these fry? What do you do with all the excess Killi fry you have, start new breeding setups, send them to other hobbysists etc?

I started with a few 10 gallon breeding tanks and now my small fish room is covered in containers with various batches of fry, I'm beginning to lose myself in all the 'Killi chaos' HELP.

Kind regards
Cameron