You could mode it to your mods folder in your technic launcher too if you'd like to have the custom textures the compled modpack provides. As for the journeymap you'll have to go into the settings on it, usually accessed with J.
You are allowed to sell some breedable BPs, but not in mass quantities. You can also neuter them or make them unbreedable and sell as many as you'd like. Read more about the rules on the Discord or in-game by doing /rules :)
If you check your inventory, you'll find a small arrow to the middle left of it. Click that and you can freely swap between the mega bracelet or the dynamax band
The world boss spawns every 66 minutes, not a wild legendary that you can capture. Giratina can actually be spawned in if you right click a Timespace Altar with a Griseous Orb after activating it with a Red Chain. The wiki has tons of good information regarding legendaries in general