3,4 and 5 require the GTk Radiant tool, or more simply, the map editor for JA. I can't help with that because I can't map.
1 requires knowledge on video and sound editing, there's no "program" for it, you just need to look through the games files and search the web for a tutorial.
2 doesn't require anything really, just find a tutorial on how NPCs are made, the NPC tool makes the whole process simpler, if you want to make your own sounds from scratch you need to know how to sound edit.
Here's a list of sites where you'll probably find the tutorials and programs your looking for:
(the site may be down)