Help euro truck simulator 2 revcounter & speedo

[topgun]

Hi peeps! I'm new here and need help.
I'd like to build a dashboard with analog gauges with lights and switches using an Arduino.

This is a planned project and I have not done anything as yet, besides looking at buying a real analog instument cluster out of an old scania truck.
I'd like to build something like gazz's omsi dash http://www.kampenwagen.co.uk/ for euro truck simulator 2.
Because arduino's are locally available to me I'd like to use them as far as possible as opposed to buying something online.
In the game I only drive scania trucks so my buttons and lights will be specific to scania only.
I'd like to use a real scania instument cluster with a revcounter and speedo with the backing lights turning on in the gauges when I turn on the truck's headlights as well as the warning lights on the dash for
Headlights
Flashing headlights on bright
Emergency flashers
Parking brake
Fuel low light etc all the warning lights in the game.
The instument cluster I've looked at is from a 1986 Scania 142 420 and it of course has all these lights on the instument cluster.

For input I'll probably hack onto the dpad of my logitech g25 and I also have a logitech rumblepad2 and a logitech driving force fx on which all the input buttons work that I can use for input. Thats the easy part.

I need help with output.

I know that the game data has to be sent from the game to the Arduino and the Arduino will send that to the instument cluster, I just don't know how any of it is done.

I'm currnetly running an 18 speed gearbox mod which ia awesome and I'm using the red input buttons on the gearshift of my g25 for the splitters but I have an idea to get a real Eaton Fuller 18 speed gearknob with the splitter levers on it and run that also with an Arduino to split the gears.

Like I mentioned before I know that this is possible, I just dont know how to do it. I read that on that gear knob I can change it from air to servo operation and connect it to the Arduino.

I don't expect anyone to do all the work of this project for me in terms of the programming and other things but if someone could explain all of this to me and how to do it and at least give me the pieces to the puzzle I'd really appreciate that and be glad to research the puzzle pieces myself.
I'm a web developer so I'll be taking the Arduino with the instument cluster to a friend of mine that does electronics for building all the hardware and wiring. Some help with the code would be appreciated or at least tell me what language it must be written in with an example and I can learn the language or get some of my old university buddies to help me with that.

Could someone also advise me on what Arduino board I should use and how many I'll need for all the functions.
Thanks guys