For#1, there i no information from the animal cells to the human cells. The pancreatic islet cells are from, say, a cow. Those cells are isolated within the cylinder and never make contact with human cells.
For #2, EVERY cell has all the DNA of every other cell. What makes a differentiated cell different from other differentiated cells are what genes are turned on and which ones are turned off. For instance, pancreatic islet cells have gene to produce insulin “turned on” so that it is transcribed to mRNA and then to protein.
Part of what makes a bone cell different from a heart cell is that the bone cell has the genes to make type I collagen, bone sialoprotein, and osteocalcin turned on while a heart cell has the genes to make calcium receptors, myosin, and desmin. But cardiac myocytes do NOT transcribe the genes for type I collagen, bone sialoprotein, and osteocalcin.
Stem cells have the cabability to differentiate into different cells types. As this process happens, the proteins specific to that cell type are expressed and proteins specific to other cell types are suppressed. That suppression is usually permanent so that a differentiated cell type cannot go back to being a stem cell.
So, embryonic stem cells are VERY primitive and it is possible for them to go down all the various differentiation lineages – form cell types. After all, they do that during embryonic development. At 5-7 days of gestation (after sperm and egg come together), ALL the cells in the embryo are embryonic stem cells. But then the various differentiation steps start happening and the result, 9 months later, is a baby with about 200 different cell types. So, taking embryonic stem cells, it is theoretically possible to generate any specific cell type: such as pancreatic islet cells.
Some adult stem cells (stem cells found in adults) are nearly as primitive. They too have the possibility to go down many if not all the differentiation lineages.
Now do you see the possible “fruits” of stem cell research? If not, keep asking and I’ll keep answering until you do.