I quickly skimmed the article, and this was what I was looking for
"After a week, slice off a small amount of cucumber and taste. If you like the level of sourness that the pickle has reached..."
If the sourness of the pickles increases with time, then the answer to your second question is yes. I don't have the answers to the other ones, but when I worked in a restaurant, our chef taught me that sour foods, like tomatoes, respond very well to salt.
This is a trend I've observed with other sour things I've consumed and prepared. Salt-rimmed glasses for lime margaritas take the focus away from 'sour' and vice versa: licking the salt off a margarita glass without drinking anything would get intolerable quickly.
Edit: I found a physiology study that supports this: the perception of saltiness is reduced by sourness (acidity).
Accordingly, the magnitude of the chorda tympani response to NaCl is enhanced at alkaline pH and inhibited at acidic pH, i.e., in mixtures of NaCl with weak organic acids
The chorda tympani is the nerve that carries signals from the tastebuds at the front of the tongue to the brain. As the cucumbers develop more lactic acid, the acidity will reduce the perceived saltiness.
Edit 2: Some more information is available on the Gustatory System Wikipedia page for salt and sour.
Saltiness is perceived primarily by an ion channel in the taste cell walls. An ion channel is a type of protein that allows ions to flow across cell walls. The particular protein for salt perception is called ENaC. Sour perception is facilitated by 3 proteins, one of which is also ENaC.
Re Question 1: I'm pretty convinced that your first question should be something more along the lines of "What are ideal salt/lactic acid ratios for lactic fermentation?" It appears that you have two variables to play with:
- How much salt you put into your pickling brine
- How long you ferment the pickles for (controlling how much lactic acid develops)
I'd venture to guess that there may be several different sweet spots for a good balance, but that generally 'too salty' can be offset with more fermentation while 'too sour' can be offset with more salt (and an immediate halt to fermentation).