I mostly want to figure out how to make Peregrine falcons appear in all places and biomes
[ALL_LAND] will do that. Adding [UBIQUITOUS] will make them appear in every region of the appropriate biome (which, in this case, is pretty much all of them). But yeah, if you want peregrine falcons available all the time, make them domestic. They're most of the way there already, having the appropriate breeding tokens, and need only the [PET] and [COMMON_DOMESTIC] tokens to make them as available as cats.
Another matter, anyone know the mineral value of an EVERYWHERE option?
I'm trying to make my custom world parameters, and I want to know if EVERYWHERE is the highest option in terms of the numbers, or if I can get it higher
Exported the worldgen settings for a pocket world, and it's 100, the minimum scarcity. You can export these setting either by going into Legends mode and pressing p, or by exporting at least one level of your fortress. To do that, you press Escape, select Export Local Image, and press Enter. By default, every layer on which you have buildings is selected. Deselect as many as you like, and press e. The game will then dump some very large pictures to your DF folder, plus three text files. You want just one of the text files, the one with 'param' in its name. This has the worldgen parameters, and you can copy these to data/init/world-gen.txt. The text file can be edited directly, though you'll need to restart DF for it to read the changes.