You can add an acid to speed up the dissolving process, since by adding acid, the limestone will become soluble in water and thus be able to dissolve. Carbon dioxide can dissolve into water to form carbonic acid, which also works.
According to gutmicrobiotaforhealth, "Colonization of the gut by the human microbiome was thought to begin at birth, but some scientists have reported that a mother-to-child transfer of commensal bacteria through the placental barrier may occur. The maternal oral microbiome has been suggested as the source of the first bacteria that colonize infants."
So we can be born with it and we can develop it as we grow.
Technically, we can. Bears and even some primates are able to hibernate, which means us humans are also able to do so.
Hibernation is "a response to cold weather and reduced food availability". We don't hibernate because our ancestors lived in warm areas where hibernation wasn't necessary for survival. Humans have only moved into colder places in the last hundred thousand years or so, so we haven't had enough time to evolve into hibernating animals.
Some humans back then actually did survive harsh winters by hibernating, but they weren't a part of the majority of the people who didn't hibernate.
According to NASA, "New Horizons launched on Jan. 19, 2006; it swung past Jupiter for a gravity boost and scientific studies in February 2007, and conducted a six-month-long reconnaissance flyby study of Pluto and its moons in summer 2015, culminating with Pluto closest approach on July 14, 2015. As part of an extended mission, pending NASA approval, the spacecraft is expected to head farther into the Kuiper Belt to examine another of the ancient, icy mini-worlds in that vast region, at least a billion miles beyond Neptune’s orbit."
Bacteria are cells. Some are pathogens (harmful) while some actually help us (such as the ones in our stomach that help us digest food). Viruses are capable of attacking our body cells and bacteria. They are both living things. Nonliving things do not reproduce, do not feed themselves in order to grow or thrive, and does not use energy (e.g. rocks, dead leaves, etc.)