I don't know if we are talking about the same concentrates here but if we are simple maths tells me your dilutions will be too weak. Each of the bottles in the 20 litre kits I use which are labeled A and C contain 250cc of concentrate. The bottle marked B contains 120cc.(2 x A. 2 x B and 2 x C in the 10 litre kit).

Divide each of these bottles by 5 because the contents will make a total of 5 litres and you get the figures I gave before.

The replenisher solution must be the same as the prime solution.

I did make a slight error in the wording regarding the starter solution where (Kodak Ektacolour RA Starter) I quoted the 80cc for 1 litre.This is is for 2 litres, however the quantities of starter is not critical so doubling the concentration would not make a great deal of difference

I cannot say about the bleach fix because I don't use Kodak Blix. I have a much cheaper alternative.

As for mixing the whole kit or half the kit at once is bad practise Diluted solutions have a very limited shelf life compared with concentrates.(Not my words - Kodak's)

I have found this to be very true and in the 20 or so years of using these kits I have never had a problem with life of either concentrates or dilutions. The concentrate in part A is the only one that has a tightly restricted life when opened but this can be assisted by keeping it in a closed light tight container in a cupboard.