(Thanks to Delfino comment)
The game actually explains the speed limits - 15 km/h on sharp turns and turns on switches, 20 km when crossing another rail and 25 km/h on switches going straight and on platforms.

It seems that 50 km/h is the top speed but shouldn't we be allowed to go faster in the tunnel? Unfortunately the manual lacks this information.

Use of bell

When on turns with weak visibility, when passing tram from opposite direction at the end (blind spot), when you want other to be aware that tram is going in motion or to made people aware if you are unsure of their intentions like crossing the route without looking around etc ....


Doors

Your choice depending on number of passengers at the stop.

NUM 4 - "hot doors button", allow to open doors which was requested to be opened by passengers due to aircon and energy use,
The photosensor will close them when no one will stand on the doors.

NUM 6 - deactivate above, its not door close button
It won't allow doors to be opened anymore, but still closing is done by photosensor, but a "bulbhead" passenger can stand on the doors blocking your departure... Common IRL

NUM 1 - All doors opens then recloses via photosensor

NUM 3 - forced door close no matter of someone stands there, it may reopen the doors but still will reclose it and be able to force close, useful IRL as well, it is not a bug that doors don't want to close with 6, it's simulated passengers standing too close to the doors as per real

If you want all doors open and staying open till you close them yourself, you have a button to override / deactivate photosensor on central touchscreen, the button in the middle.

On the same screen there is a ramp button for first and last doors to remain open, ex for pushchair or wheelchair user to not get hit by doors (ramps are on first and last doors).


Lights

Passenger lights are behind the seat (left side rear panel) on the right of Notlights.

Cabin lights are on the right dashboard.
Below is a speed limiter (useful on some parts of the road) .


Timetables
For those catching the tram in front.
You go way too fast or do not respect the departure times. Trams cannot go too fast on curves, going on 90deg tight turn its like 10km/h IRL. Anywhere where the tracks turns there is a limited speed to be observed IRL, due to derailment or breaking the bends possibility (no differential on wheel axes) and very shallow, narrow rail.

Timetable and time can be chosen from top menu in game, put your mouse top screen and you will see a little black background, press LMB (left mouse button) and there you can select timetable from multiple services and their timings, also you can adjust in game current time and choose to show points on the HUD (good to know how well you stopped).

On the right screen you will see a difference of time to the timetable in minutes
- will be ahead of time
+ will be delay


Reverser
Reverser is modelled with all modes but INOP in-game yet.
We can go only forward for now.