Hi,
first of all: welcome to Zusi and the forum!
I'm not going to be able to answer every question of yours, but I'll see what I can do.
About the good timetables: that's most definitely subjective. I personally really enjoy the newer routes and vehicles, so the SFS (High-Speed-Route) between Kassel-Wilhelmshöhe and Göttingen is really great for getting to terms with the LZB. I'd recommend starting with a low chaos level, to avoid difficult situations while getting used to the standard operation of the LZB. The VDE8 is fantastic, but requires you to learn to operate ETCS, which is very different from the earlier systems in Germany. For a wide variety of vehicles on routes which might be familiar to you from the demo, I'd suggest the Bahnhofsfest Altenbeken timetable from the Paderborn_Kassel folder. All of these timetables are relatively current, so some rule changes apply in comparison to the demo, probably one of the more notable ones being not having to use the whistle before entering tunnels. Also the Buchfahrplan/schedule is using a slightly different layout and contains more information. The ¥-symbol e.g. symbolises the point of the last switch behind a signal, i.e. the point after which you can accelerate after passing it with the last axle of your train.
For the older electric trains, I think the best one is currently the 151. It has a dynamic brake in addition to the pneumatic one, has a Full-HD cab, and is a lot of fun. Please note the limitation to a specific amperage (not sure about the value right now), so if you try to accelerate too fast the main breaker will trip.
I'm not sure about the English documentation, but considering I'm not even aware of German documentation explaining the usage of modern trains (except for the PZB90 and the LZB) I doubt there is any. But if I'm honest, they're actually a lot easier to use than the old ones. Probably the thing that confused me the most about e.g. the 120 is the way the driving controls are arranged, especially on keyboards. Some of them have a +/- range, so the first three positions are "reduce traction, hold traction and increase traction", and you have to hold the button to pass forward into the range which allows you to set the traction directly. And I'd recommend using the AFB, basically cruise control for trains. I'm not sure about the keyboard layout, as I'm using a custom one, but you'll have to switch it on and then use the lever left from your traction lever to set your desired speed. Note that you can only turn on the AFB if your traction lever is set to 0, and if you turn on the AFB while rolling you will want to set the AFB lever to maximum before turning it on, to avoid the train braking, because the AFB is set to a speed of 0km/h. When using the AFB the train will accelerate automatically, but only with up to the amount of traction set by your traction lever, so it won't accelerate if it's set to 0.
ZusiDisplay
should work out of the box, if you're running it on the same computer as the simulation, but you'll have to enable the data transmission in the network settings of the simulator.
I'm not sure about the specific translation of "unsafe driving" in this case, so I'm not sure about your evaluation. Maybe you could provide a screenshot or the result xml, so we could have a look at it together
In the hopes of having helped a bit, have fun driving!
halfur