12V DC Model Train Arduino controller simulating momentum

Having kids now I thought its time to dust off the old model train set - nothing fancy just plain old 12V DC model.

When I was about 16 I etched and build an analogue controller to replace the stock transformer and I was amazed at the result - no longer did I have to go push start a Locomotive on the other end of the room! With this unit I had a momentum, brake and emergency brake in addition to the throttle.

One day I still plan to reverse engineer (the wrong word here) since it will be more like PCB archeology in this case.

So back to today and being the wrong side of 40... So I got a free breadboard, Arduino, LM298 and display and got busy. I have a basic prototype but not ready for the tracks...

Aims

Hoping to make it easy to use - perhaps switching off momentum etc. else the kids will loose interest, and mum will cut subsequent funding for this project.

Safe so that if they flip the direction, the train should at least slow down first before speeding up in the other direction... even limiting top speed.

Simultate momentum, not true to scale but perhaps adustable depending user.

Brakes, Emergency brake, Direction and throttle.

Questions:

1. I have searched for similar projects on the web / Elektor but no success. Is there something I missed? Since that might just put a brake on this proposal...
2. Simulating momentum. Since I completed school before momentum was discovered I currently simulate this with a weighted average of a PWM output over a 5-second period. I found some research papers about real world train controller maths, but the maths would be too much for the Arduino I guess ;-)
3. I have not yet hooked up an Oscilloscope but I have seen other clever clogs complaining the the H-Bridge LM298 output might not be the best for a 12V DC motor. This I need to investigate further. Any jump starters?