Atom, cell, tissue, organ
Insulin causes blood glucose levels to drop, which signals the pancreas to stop producing insulin in a negative feedback loop. Hormonal stimuli refer to the release of a hormone in response to another hormone. A number of endocrine glands release hormones when stimulated by hormones released by other endocrine organs.
It is 0%. They only have the recessive alleles (ss) so there is no possibility it can ever produce a gamete with a dominant allele (S). For example, if it was Ss it would be 50%, and for SS it would be 100%.