The issue of a deterring punishment is not just the severity of the punishment but primarily the chances of being caught.
Unfortunately, it is very costly to put a policeman in every kilometer.
Moreover, much of the problem is speedy driving inside city streets - not just along the highways.
Therefore, the solution should be to certify veteran drivers with the legal authorization right to remove from the road (until the police arrives) aggresive-careless drivers.
I see these road-killers almost every day, and feel hopeless. I wish I had the legal authority to stop them.
The police must ask the "good people" to help catch these reckless drivers. Some kind of volunteer-police-assistant card will be issued to veteran drivers with good driving history.

1) Regarding speed:
One of the mistakes many people make, is to believe the statistics, that speed is not a major cause.
This is nonsense, and let me explain why.
Speed does not cause the accident - another mistake or technical problem causes it. However, in low speed the accident could be prevented DESPITE the other mistake.
Starting with problems like tire explotion, bumps on the road or sharp turns in the road - these are considered "causes of accidents" - not the speed - but lower speed would have prevented the accident despite the other causes.
Or simply think about the fact that in different occassions you suddenly must do something within a certain driving distance of, say, 50 meters - otherwise an accident occurs. Suppose someone stopped in front of you, and you must stop too. Obviously, if the speed is high you have fewer seconds to react and the chances of preventing the accident is lower.
So high speed does not cause accidents - it just prevents the prevention of accidents which are caused by other problems. And the official statistics show "other causes - not speed", but it's false.

And of course - if accidents happen anyway - the severity of damage to passengers is smaller in low speed. Once again - speed is not a cause for the accident - but it is the cause for the suffering.

2) Regarding traffic volunteers: If somebody issues a false complaint (as you mention), it is likely to be detected in court - just like any other false testimony, and the liar wil be prosecuted.
My suggestion is that the certified driver, will stop the reckless driver on the spot (if possible), and stay there with him until the police arrives. Of course multiple witnesses are preferrable - but the general idea is important - that there aren't enough police officers, and ordinary drivers should be asked to assist.

3) I believe NERVOUS driving in a highway, such as "zip-zag" passing from lane to lane, "cutting" someone with a minimal distance in front of his car is very dangerous even in reasonable speed, but officially, this might not be considered a violation.

1. What you're saying seems to always assume the driver is NOT KEEPING HIS DISTANCE. That's the reason for accidents, not speed. Keep your distance, and even in 200KMH you'll manage to stop in time (it'll be one hell of a distance, though). Problem in Israel is people just don't keep that distance, and so never manage to stop in time. (I'm talking about instercity roads, of course, where pedestrians are not a problem).

2. Ha! If you trust the courts when it comes to traffic offences, you've got another thing coming. With so much business in their hands, the last thing they'd care to do is launch a full investigation as to the sincerety of the complaining party. You say he drove 80 inside town? OK. You say you weren't even in the country? I don't care. 1000NIS fine. NEXT CASE!