Copy and pasting and code scan only come up in a few dungeons later, don't worry. Just have a kinda balanced team in your party you can do most hacks.
The gate hacks are used throughout the game to progress to the next level of Kowloon.
The next three (including Copy/Paste) are used later in the game to solve light puzzles.
Then the next five reduce/eliminate encounters or increase/instantly cause them.
If you check your profile card you can see the requirements to unlock each skill but remember that you need to maintain the requirements to use the skill. If you stop meeting them you will lose the ability until you do.
Thanks, also find out you can cast evasion and attraction on yourself. I was wondering why there were no items like that in game.