Hey there.
The mod folder can be found here
On Windows: C:\Users\[username]\AppData\LocalLow\Glitch Pitch\Idol Manager\Mods
On Mac: ~/Library/Application Support/Glitch Pitch/Idol Manager/Mods/ *or* ~/Library/Application Support/unity.Glitch Pitch.Idol Manager/Mods/
As for the freezing, if it only happens once and for five seconds, it could be related to your machine. If you see it happen more frequently than that, or if the game hangs for longer periods of time, you should send an e-mail to sadambober@gmail.com with a brief description of your issue, and your save file attached (save files can be found at C:\Users\*username*\AppData\LocalLow\Glitch Pitch\Idol Manager\data\story_mode\*groupname*\ on Windows or ~/Library/Application Support/Glitch Pitch/Idol Manager/data/story_mode/*GroupName* on Mac)