Hi dvarrin,
As someone who has just embarked on this process myself I can offer you what I have learnt so far.
- Where can we buy all those switches and buttons, Especially the buttons having a protection cover as in an aircraft?
Any electronic component store really. I believe Radio Shack in the US sells some of this but a good site is RS Components or Farnell (google them). You are looking for Toggle Switches and more specifically, double throw toggle switches. The covers you speak can normally be found in the Accessories section of of the switches area.
- How do you do the connection with the computer. How many buttons can we have for a joystick and what do we need for the interface with the computer?
You need a USB interface. I got mine from GroovyGameGear.com and it will support 32 buttons as if you had a 32 button joystick.
- How do you put lables on the metal plates?
This one I am still trying to work out. Particularly since we are talking white writing on a black surface which is not common. Still working this one out I'm afraid.
- Where do we find gauges and how do we make them showing the same informations as the gauges in the game?
That is complex. Several gauges exist but they will require programing to get them to read and display values from A-10. If you feel you are up to it I might be able to provide a few links. But this is not for the faint hearted. Building a panel is one thing, getting interactive info from the sim to a gauge is whole other thing.