I've been trying different setups for a few years. If converting a road bike with a freehub I suppose an 8-10 speed freehub is preferable to an 11 speed freehub, though I don't know that from experience. You could use Shimano, Origin8, and Wheels Manufacturing for cogs and spacers. The threaded freewheel hubs are generally significantly longer in between flanges from what I've noticed. But, you said you weren't interested in fixies and you don't need to get into threaded hubs. If you are interested in track style riding then I think a threaded hub may be preferable.

You may need a vice, specific vice wrench, chain whip, lockring spanner, and cassette/freewheel removal tools, though maybe not all of them. I'm currently deciding between a Pedro's vice wrench and a chain whip style lockring tool, and would go for the vice tool if I was working.