Are you a passenger in the train of which the ped should drive? In your client-side script you are declaring the Engineer as the driver of the vehicle you're in.
Looking at the example on wiki page it has
actualspeed = (speedx^2 + speedy^2 + speedz^2)^(0.5)
So maybe that is the formula for getting the speed, not the velocity. Remember for it to work;
speedx,speedy,speedz = getElementVelocity(...)
On my desktop (IE and laptop (Google Chrome), they all have a picture-border with text saying "User atavar", which I presume is the alt="" for the image.
All the avatars on the forum have failed and no longer show. It appears to be https://forum.multitheftauto.com/download/file.php which is no longer working.
That's not really a feature for the MTA developers to add, it's a job for each individual server's owner. Like djlobo said, you can script cops by using the ped functions (see wiki page.)
1. any function requires a () after it's name.
2. End's do not require the function name after them.
3. Bind key has 4 args, look at the wiki page.
If you want a menu, look into GUI or DX (I'd go with GUI).