Welcome to LibriVox! Good to have you join us.
To answer your questions:
1) Yes, perfectly OK to read the test in any language you prefer. It would be nice if the text had some hard 'p's and 'f's, to see how your microphone setup handles potential "plosives". The only requirement is that the text/fragment is in the Public Domain.
2) Yes, we do follow the US law because the final production files are kept in the US. In addition, you are to adhere to any local laws while recording in that locality.
3) No, that's not correct. There are so few of us here that a collaborative project in Russian is rare (I don't recall any). You can/may start a solo if you are up to it, a suggestion to join a group project is just so you can learn the process without too much to handle at once. One reasonable collaborative contribution you could make is to the current "multi-lingual short works collection".
Do ask any other questions you might have, we'll be happy to help.
Again, welcome, and hope to hear you around soon!
