As a guy who was working through all these same questions last year at this time...
Here's my 2 cents...
I'd avoid making anything permanent until you get some experience. I built my hive stand frame out of 2x8x10's and placed that atop 1 1/2 cinder blocks on each end. Going into next Spring, I think I'll change both it's height and location.
As for how far apart...some folks butt their hives together, I like to leave room to fit my hive tool comfortable between them. This allows me to work a hive from either side, without being restricted by another.