What does each cheat codes do?
They are not technically "cheat codes" they are more of "unlockable free stuff/DLC". This list is based on the comment of someone in this forum/thread a couple of pages ago.
USEFUL codes/IRISCODES
3489641 - Dille and Elle Show Up - Adds Dille & Elle to your party. (Two girls but one character.) Access the event which adds them in Domestic Affairs.
^Pretty Good Farming unit
6429691 - Ariadne's Fleshlight - Throwing equipment "Massive Hole" can be obtained from Domestic Affairs.
2467118 - Yushia's Fleshlight - Throwing equipment "Two-Hole Gorgeous" can be obtained from Domestic Affairs.
4867723 - Luluka's Fleshlight - Throwing equipment "Tighty-Tighty" can be obtained from Domestic Affairs.
The three weapons/throwing equipment stated above are good early-mid game weapons and it's "free" but it's easily outclassed at mid-lategame.
1567820 - Anime Special 1 - The "Soap Mat Sliding" active ability for Ariadne can be learned from Domestic Affairs.
^Good Skill it gives a lot of movespeed and causes knockback when colliding with enemies. It's also goofy as hell visual wise with the soap mat
7246882 - Anime Special 2
^This seems to give 3 Brothel Events. CG not found (not sure but it's not on gallery and I don't play brothel mini game) in game. One is Harem event while the girls practice with you for their brothel duties. The other two is the same CG as in the first event but the dialogue/CG might vary a little bit since this time the girls are performing brothel duty on random people with that CG.
For the next two I will use what the user describes it (Their descriptions are with quotation marks"") from whom I've obtained the details.
0114106 - Malice edition clear - "unlocks three endgame-level brothel scenes which can be watched from Domestic Affairs."
^That description may be false since the one that unlocks the brothel scenes are Anime Special 2
5951245 - Colored paper gift for voice actors - "Unlocks... nothing? Edit: maybe this one unlocks the brothel scenes in Domestic Affairs? If so then what's Malice do? Idk."
^That description may be false since the one that unlocks the brothel scenes are Anime Special 2
So with that in mind the last two IRISCODE are quite a mystery at the moment (nobody knows what they do)