People have many ancestors: You had a father and mother. Your father and mother also had a father and mother, and so on back into ancient times.
A common ancestor is on that has given rise to two or more lines of descent.
No
divergence.
The branch point in a cladogram represents a specific ancestor that is separated into two or more species. For example a leopard and a house cat share a common ancestor. A similar example is that a wolf shares a common ancestor with the leopard's and house cat's ancestor but the wolf's ancestor lived longer than the leopard's and house cat's ancestor. Scientists use something called cladistics to determine the one common ancestor that multiple species have in common.
Biology classified organism by evolutionary link thus one with the closest common ancestor would put it near each other. Though one from a far ancestor might have more similar appearance than their relatives. It is just how evolution work.
No
I guess no. But I would not quote on that even.
Bad. Because every antivirus works in its own way...
No the more musical works you do the better :)
You are always their ancestor. The people who call you their ancestor are your descendants.
A group of species that consists of a common ancestor and all of its descendants (also referred to as a clade).
Yes they can. Sometimes they're good, sometimes bad.