Mindboards

is there a way to up/download files to/from the EV3 bric on linux via USB?

ie. is there a dll.exe that works on linux, or a nxttools that works with EV3?

If you look at the ev3sources documentation, the communication protocol is defined there, including the send/recieve file parts:
http://python-ev3.org/communication.html

you also may use the file explorer tool provided by BCC