First of all, in case you don't know already, every window in the program has context sensitive help, so if you have any questions about how to use some of the features mentioned below, just find the window and press F1.
1) Special functions can be activated by different buttons. A special function's activation parameter, for example, can tell the system the the function should only activate if the player is pressing button 1 (gamepad button 1 or whatever key is mapped to button number 1).
2) There is a sample of a 2-player game at
http://gamedevprj.sf.net/files/ (see file GD2Player.zip) and some discussion about it here:
http://gamedev.comdel.net/index.php?topic=656.03) The kit does not generate code. It just saves data about the graphics, maps and parameters you have specified. The GDP file is the top level file and can be viewed in notepad. The MAP files are binary and contain a lot of the data for the individual maps. But if you export the project to XML, you can see all the GDP and MAP data in plain text. The actual code that runs is in GameDev itself (GDPlay.exe or GameDev.exe -- GDPlay is a runtime-only version of GameDev.exe). If you want to see it you'll have to download the source code package.
4) The recently posted project "Bob the Unlikely" (
http://gamedevprj.sf.net/) used sprites to display messages. The whole message was stored as a graphics and then created as a sprite. Otherwise, you don't have much control over how messages get displayed unless you use script. I would have to know more details about what you're doing to explain what's going on with the "sluggish" timing. Obviously GameDev is responding pretty quickly most of the time, so I don't think it's really "sluggish" but rather some design anomaly that is causing certain keys under certain circumstances not to react at all. Your message may be ending up in the background buffer and not flipping to the front where it's visible or something.