It is exactly what the name states, it is a flight simulator, it is as realistic as you can get (besides Microsoft Flight Simulator X).
No, Microsoft Flight Simulator 2004 add-on aircraft cannot be transferred to Microsoft Flight Simulator X.
Yes, you can download add-ons for Microsoft Flight Simulator 2004.
To open aircraft doors in Microsoft Flight Simulator 2004, press: Shift + E.
Yes, you can get a Dash-8 in Microsoft Flight Simulator 2004 by downloading a Dash-8 add-on. Just type "Flight Simulator 2004 Dash-8" into a search engine.
You can't, the coding on the planes is different. Most of the planes you find in Microsoft Flight Simulator 2004 are available in Microsoft Flight Simulator X.
There is no need to buy Microsoft Flight Simulator X: Deluxe Edition as Microsoft Flight Simulator X: Acceleration contains everything from Microsoft Flight Simulator X: Deluxe Edition and more.
You cannot download Microsoft Flight Simulator 2004, you have to buy it.
Yes, you can play Microsoft Flight Simulator 2004 without a disc. I have put a link under this question explaining how to play Microsoft Flight Simulator 2004 without a disc. I have put a link instead of explaning how to do this because of the amount of steps.
You cannot play Microsoft Flight Simulator 2004 anywhere online. One, it would be illegal, and two, it needs to be installed on your computer.
No, you cannot use the add-ons for Microsoft Flight Simulator 98 in Microsoft Flight Simulator X.
Flight Simulator X is by Microsoft, the full name is Microsoft Flight Simulator X.
you wont get it muhahaha