These requirements were originally a couple hundred years as a ghoul, but to make them feasible player characters I cut the time down if the ghoul commited some courageous, beyond the line of duty task that impressed the vampires. Yojimbo are usually large, very large. Yojimbo's that aren't very large have other impressive abilities that serve them well as bodyguards. Yojimbo's generally live with their employer, though recently more and more freelance Yojimbo's have appeared. They can live just about anywhere.
Physical attributes are primary, as are Talents or skills.
The Yojimbo are more susceptible to the blood bond than any other clan. Two points of blood over two nights is sufficient to blood bond a Yojimbo.