-Will you add unofficial characters, like the japanese Lost Worlds books by circle KASU?
-None of those are scanned (as far as I know), so I can't add them.

-Do I have to add all the available characters to play this game?
-No, you can choose to have any combination of QB or LW characters you want and still be able to play. Some game modes require specific characters depending on who you choose (like Arcade), or others  require a minimum number of characters (like Tournament), but you get properly warned if you don't meet the requirements.
You can remove a character at any given time just by taking their image folder out of the "chars" folder.

-The game crashes on startup for me.
-You're probably missing Microsoft visual C++.
For a 32 bits OS, download it here (or for 64 bits, here). If you keep getting errors on startup (especially if they mention a "Core" or "System.ServiceModel"), you might need to uninstall .NET 1.0 and 2.0, and search and reinstall .NET 3.0, 3.5 and 4.0, and that should fix it.
The music system used to cause errors in the past, but hopefully now just gives you a warning and you can add "nosound" at the end of the CFG file if it fails.

-I can't connect to my buddy's IP in the Online Match mode. What's wrong?
-If you're contacting them through a WAN and you've already made sure you're not actually using their private IP (the ones that start with 192.168.x.x), that's probably because their router is blocking the transfer to that port. Your buddy will either need to forward that port (google "port forward" for the precise instructions for that router) or use Hamachi and create a VPN between both your computers (though I haven't tried that myself, I'm pretty sure it has to work)

-I noticed this bug/glitch...
-If you notice something unusual about the game, I'd appreciate it if you let me know about as many details as possible, like the characters you and your opponent were using, or the attacks that were taking place. Or, if possible, just take a picture of the bug and it'll probably give me all the information I need to correct it.