I like how this vampire makes the "action or bonus action but not both" of slow meaningful & the legendary actions would definitely allow the vampire to whimsically toy with prey before misting off to the rafters or something 

I was about to comment on that! It's a really interesting addition. I'm getting some cool visuals from it. The victim tossing and turning in their sleep as visions of the vampire or being stalked prevent them from truly resting, until they wake up with a start and feel compelled to meet with the vampire.I love the strife inflicted by a vampire bite. It affects you even after the encounter!
Personally I prefer if it just say vampire. We are not fools, we know it is a spawn and not a full fledged vampire. Why waste space on saying spawn all the time. Not in the MM, the dragong stat block doesn't say "blue dragon" through out its stat block, it just says "dragon." This is the better way to go IMO.Love it.
A small correction in the Regeneration entry of the vampire spawn.
It says that "the vampire regenerates 10 hp" the entry should say "the vampire SPAWN regenerates 10 hp...". The same occurs in the Monster Manual.
Personally I prefer if it just say vampire. We are not fools, we know it is a spawn and not a full fledged vampire. Why waste space on saying spawn all the time. Not in the MM, the dragong stat block doesn't say "blue dragon" through out its stat block, it just says "dragon." This is the better way to go IMO.
Not IMO. It is a type of vampire, like a blue dragon is a type of dragon. I believe one of the developers of 5e mentioned that "vampire spawn" are typical vampires and "vampires" in the MM are what some would call "vampire lords." That is basically how I see it. Back in 2e, I believe, you could advance a vampire based on its age. I look at the vampire entry in the MM and LevelUp the same way. All the entries here are listed under "Vampires," so they are just different types (or in my mind ages) of vampire.Then maybe it should be The spawn, instead of the vampire?
Not an error. It's the standard way D&D does it with monster variants in the MM. We didn't feel any need to change that. YMMV.Love it.
A small correction in the Regeneration entry of the vampire spawn.
It says that "the vampire regenerates 10 hp" the entry should say "the vampire SPAWN regenerates 10 hp...". The same occurs in the Monster Manual.