If youre uncertain, reach out to the broader MTG community for help
Its ideal in a vampire-themed deck, but Id consider it for any vampire commander, since youll always have access to at least one every game
Potentially, there could be fewer than 77 copies in the entire world, but its difficult to speculate on that
The first three are obviously absurdly good, the Staff can be painful but well worth it if you can offset the lifeloss with Venser's lifegain
Im trying to remain objective here, but Saskia the Unyielding has such a good aim in trying to make low-to-the-ground aggro viable in the 40-life Commander format, and shes got a penchant for leading off the Wall-themed decks, especially the various creature themes, be it Human, Phyrexian, Angel, or Werewolf