Many people will stand up after bringing the bar down, then bend down re-grip and pull for the next rep. That would be a full reset.
I don't do that. I let the weight hit the ground and I release tension, then grip and rip, ie I stay down. I do this because I think standing and rebending is overkill, for me, and would probably give me a head rush. It's impotant to do some sort of reset though. Basically, the weght is generally so high that any flaw in your technique is a substantial risk, so you want to take a second to ensure you and the bar are in the proper position to execute the pull. If you just let the plates touch and then go, you could be significantly off of your best form, especially a few reps in. You risk missing the lift, or worse, injury.
As for your balance question: deads are a hip extension exercise, so the antagonist would be hip flexion--hanging leg raises are a good example. Their are those that will disagree with me, but I don't think doing direct antagonists are as impotant on lower body movements. I'm not saying balance isn't important, it is, it's just the idea if you pull in one plane, that you should also push in the same plane doesn't work as neatly with the lower body as it does with the upper. Just look at the different loads between deads and leg raises.
I think a better way to get balance as it relates to deads and squats is to keep up on the accessory movements. Do GHR, RDL, sidebends, ab work, rev hypers, back ext., etc. That way you're developing the entire girdle and not neglecting anything.