I'm interested in jumping into strobes but I'm a bit confused. It's a lot to take in for a beginner so I'd appreciate advice on getting started.

My budget is flexible but I'm thinking of starting off with roughly $1k. I value size, portability, weight, and ease-of-use because my interest is on on-site work that is both indoors and outdoors. I'm most interested in the 50's-60's fashion/portrait photographers (e.g. Henry Clarke, Irving Penn, Richard Avedon). I'm no lighting/portrait expert but i believe that these great photographers used north-facing window light or had a simple strobe settup. I guess I want a look that is well-illuminated and soft. I'm not interested in hard shadows or multi-light configurations: I prefer something that is soft and natural-looking.

This is what I was thinking:
-monolight: Alienbees B800 or Einsteen E640. Anyone have experience with these? I'm only interested in black and white, so would color inconsistencies be an issue? Why would one get Einsteen's over Alienbees?
-modifier: I'm not sure which to go for. Either a softbox, umbrella, or PLM umbrella system. I believe a softbox is softer and more directional but the umbrella has more contrast and is more spread. I'm not so familiar on how PLM umbrellas work, but it seems that they are able to mimic both? Any advice on which to start off with? I have more interest in outside, if that matters.
-stands: I haven't looked into this much as it seems like a lesser issue, but any recommended brands?
-vagabond mini lithium: This seems to get great reviews.

Am I missing anything? I have a tripod + head, reflector + reflector stand, and a flash meter kind of figured out. And I will pick up sandbags.