SunPak 383 or Vivitar 283? Off-camera lighting

[xibo]

Okay, so I'm looking to use a flash on a stand with an umbrella to fool around with. After reading around I saw that the vivitar 283 and sunpak 383 are mentioned quite often as being reliable and widely used for this purpose. Is this correct? Now, is there any particular benefit to using one over the other? I'm also wondering about attaching a slave unit. What kind do these accomodate? The only slaves I've seen are a peanut one that had a sort of pointy connection and a micro one that had a connection that looked like a wall plug. Would either of these work? (sorry, I'm super new to this!). I also have purchased an AC slave to go along with the flash and for lower lighting demands. Any help would be much appreciated!

Also, I purchased a sigma flash of some sort that has a built in slave so I can experiment with that before I order the vivitar or sunpak (which I will keep). I'm going to return the sigma because it was $300 which I really can't afford. I know, I know. I should just wait for the one I'm buying but I hate waiting !! Anyway, I've been trying to use it but can't seem to get it to synch with my camera. What might my problem be there?