You may reuse brine only if it is to refrigerate something such as refrigerator pickles. If it is cloudy or murky, do not reuse. Also, you cannot use pre-used brine for canning.
pickles
I have frequently reused pickle brine in recipes asking for vinegar. It has more interesting flavor than regular vinegar. I have no idea if it can be reused for pickling though.
They are actually cucumbers soaked in brine
The correct spelling of the plural noun is "pickles" (normally cucumbers in brine).
cucumbers and brine vinegar soak the cucumbers in the vinegar for about 48 hours
Any vegetable that has been pickled, whether in vinegar or brine, is an acid.
It really depends on the intesity of the flavor you want and the kind of pickle you're making - the standard benchmark is about 2 weeks. They only take about 2 days to absorb the briny flavor, though. 2-day old pickles are known as "new pickles", while the older ones are known as "old pickles".
Pickles are actually cucumbers that are fermented in vinagar or brine to preserve them. That is where they get their sour taste. It is not known specifically where the pickling process comes from, however the earliest known use of the term originates from somewhere in central Europe circa 1440 A.D.
Pickles are not typically wrapped in aluminum foil because they are already preserved in vinegar or brine, making them less likely to spoil or become contaminated. Additionally, pickles are often stored in jars or containers with tight-fitting lids to maintain their freshness and prevent exposure to air. Wrapping them in aluminum foil may not provide any additional benefit.
Typically, there are no seeds in a pickle. Pickles are cucumbers that have been pickled in vinegar or brine, which does not involve keeping the seeds.
The brine in sauerkraut and pickles contains to retardants to alcohol production, salt and vinegar. Salt kills yeast that eats sugars to produce alcohol. Vinegar is the end product of alcohol production.