Hi @alfybe, below the answers:
No, as of now this isn't possible. Only a few plugins support/require audio files but nothing stop us in the future to support it.
The plugin store is available in the MOD UI accessible through the browser when you connect the MOD using a USB cable. It's the last tab at the bottom left of your screen. It only works when you're connected using your computer.
We're working on bringing a User Guide with a step-by-step for most of the features including videos and examples. Will let you know when we have it available.
We capture feature requests either here in the forum (there's a Features categories) or in our mod-duo-issues project in GitHub: https://github.com/moddevices/mod-duo-issues/issues .
Feel free to post any ideas and the more people/up votes you get, the more likely it is that we'll implement it. There are already a few cases of improvements being implemented out of discussions that happened in this forum for example.
Thanks and welcome aboard!