Correct answers posted above... but all reports I've read indicate that Kodak RA4 developer (I bought the same kits as you) keeps better mixed to stock solutions than as opened concentrates. The advice I got here was to make up one full 5L batch of developer and store it in an aluminised mylar bag (wine/water cask).
I don't believe you need to mix up the blix and personally I think it's probably a slightly bad idea because (as a generalisation), bleaches eat fixes when mixed. I did find with the Kodak chems that you cannot run the bleach and fix separately; there are buffering agents in the fix that are required to get the pH of the bleach correct and remove all the silver. Running them separately gives retained silver in the prints (high contrast, low saturation).
For blix replenishment, I have mixed my bleach and fix concentrates into two "half mixes" (2.5L each) with water; when I want to do 20mL of blix replenishment I just use 10mL of each half-mix. That keeps them separate in the long-term on the shelf (combined only in the working solution) but makes the replenishment process pretty easy because I don't need to do dilution at that point.
If you're using a Jobo like me, oxidation is an issue. You will probably kill a 2L working solution from oxidation before it runs its official capacity, so you're better off (IMHO) running about 250mL of working solution, which means it gets turned over completely by replenishment (15mL/sheet, though in theory 10 is acceptable) every 16 sheets instead of 130. I've used only a few mL of starter (for the 250mL) and just kept on replenishing that and never starting a new batch. It keeps really well on the shelf, unrefrigerated, as long as you exclude oxygen with butane.
Edit: just saw your trays note; disregard the above. 2L will be fine I'm sure.
Last edited by polyglot; 11-01-2012 at 11:23 PM. Click to view previous post history.