Honestly, I wouldn't trust a digital camera with my exposure metering for LF. Get a good flash meter for that, then work out all your calculations from there. Digital sensors are somewhat different than film in terms of response to light. There is a reason that Seikonic makes a meter that will profile your digital camera. Manufacturers can only bet trusted so far.

On the other hand, I think it's about the best idea in the world to tether a digital camera and shoot it to get a sense of the lighting itself, in terms of light placement and relative intensity. Its just plain cheaper to snap a digital image, look at it on a nice screen, then adjust your light placement accordingly. Modeling lights are pretty vague I've found.

And yes, get a safe sync. Better to spend a few dollars there than a few thousand on a replacement camera. Oh the joys of electronics.