First of all - most developers are staining to some degree. Large sulfite concentrations tend to diminish the strain, as do acid baths. Hydrochinon is very similar to pyrocatechin chemically speaking, and also gives a good stain under the right circumstances.

The pink dye of some films washes out faster in alkaline solution, I don't think it has anything to do with alkalinity.

I use my fixer (OF-1) undiluted, but have tried it diluted 1:1 just to get more volume. Works just as well, but a bit slower.

The bicarbonate can be replaced with metaborate. I used bicarbonate since I wanted as much as possible to be available off the supermarket shelves. The pH will be similar; about 8.5 which is what I wanted: alkaline enough to get the benefits of that, while being low enough to stop most developers.