Thereof, is it easy to hack 3ds?
If you would like to homebrew 3DS, a Free homebrew exploit is the most suitable, it's free and easy to setup. If you persue more modding on Nintendo 3DS, such as run . CIA 3ds games or Backup, edit, and restore saves for many games, then install CFW on 3DS via the NTRboot Method is the best option.
Similarly, can you go online with a hacked 3ds? If you're asking if it's dangerous to go online with CFW, it's not. You can go online all you want. Just don't use hacked Pokémon, that will probably get you banned.
Likewise, is modding 3ds illegal?
It is not illegal, though Nintendo does not like it, I don't think you have anything to worry about, as long as you're not using their SDK or modifying the system firmware.
Can you Unbrick a 3ds?
Magnethax, as it's been nicknamed, will allegedly let people unbrick all models of 3DS, including the New 3DS and the 2DS. Of course, this will only work for software-based issues (such as a NAND gone wrong), and not hardware problems (e.g. MCU bricks).
