Download the most recent NPC.ini and put it in the cave story folder you are editing. As for putting giant ballos in, that's a special boss and therefore you need to put Ballos under boss in the map you're trying to edit. You can only have 1 special boss in a map so if you're planning to do something like make a room full of ballosses. Also you should have searched cause I'm pretty certain that there's an answer somewhere in the forums.http://spgardebiter.sp.funpic.de/CaveStory/Programs/
Assuming you mean the sound effects. Download Pixtone.exe off the tribute site. It can open or create new Pxt sound effects and it can save them as pxt and wav but it can't open wav files so you can't convert them into pxt so you'll have to recreate them using the program. I'm not so sure how to import pxt files into the game but I don't bother cause cave story already has enough good sound effects.