How hard is it compared to B&W to get quality and consistency?
C41 is not much more complicated than B&W. No special equipment is needed. I use water bath tempering for the chemistry (bottles in a dishpan of hot water ~140F, and start processing when temperature stabilizes at about 101F). Only the developer (first solution) is particularly temperature sensitive. Thus you only need to be between 99-101F for about 3 1/2 minutes. I hold the small tank (Nikkor two-reel tank) in the tempering bath in between inversions for agitation.
How toxic are the chemicals?
Not very unless you are sensitized to developing agents. You should have little or no more chemical exposure than for processing B&W in small tanks. Stop bath is acetic acid/sodium bisulfite and fixer is quite similar to what you are using now. Bleach is primarily Ferric-EDTA and while it can be corrosive to stainless steel, the short exposure of processing isn't a problem. It does not appear to present any dermatitis problem, although there are alternative bleach formulae that are not so benign. CD3 and CD4 developing agents are more complicated, but toxicity is somewhat comparable to phenidone that is used in many B&W developers. I will defer to experts on this, but have not had any problems when following good lab procedure and the normal practice for small tank processing. Stabilizer contains formaldehyde, but it is my understanding that stabilizer is not needed for the current generation of C41 and RA4. I continue to use the formaldehyde-based stabilizer perhaps more out of habit than for any other reason. I do use photo sponges to wipe film after a couple of minutes in the stabilizer before it is left to air-dry.
Can you use the same tanks and reels you use for b&w?
Yes, but water bath tempering is facilitated by using SS tanks and reels owing to their improved thermal conductivity. Otherwise it's exactly the same as for B&W processing with a bleach step added before the fixer.
How cost effective is it?
Probably not as cheap as WallyMart processing, but a lot better for quality and consistency and certainly for convenience. I use scratch-mix chemistry exclusively. See the Alternative C41 thread for discussions of this approach. There are also threads with lots of information on dividing Kodak and other chemistry into more convenient sizes. I mix and use 1-liter size and process for a few weeks before renewing the developer. I use stop, bleach, and fix to exhaustion as determined by observable activity taking half the processing time. Usually these solutions last a lot longer and can be used for quite a few rolls before being replaced.
How long is Kodak likely to make the chemicals?
I defer to PE for comment on this, but likely as long as they are in the film business. Kodak supplies a lot of small independent processors and obviously they are going to support their films for as long as possible. Read that statement to mean until some corporate raider decides the company assets are worth more than the stock and buys Kodak for liquidation. Kodak has gone into the digital market very heavily in an attempt to stay afloat. I expect they are going to be in the chemistry business longer than a few other big outfits we can name like Braniff, Ozark, Eastern, Western, TWA, etc.
