1. Time-stretch is based on a percentage, from 25% to 200%. You can adjust the value in real-time (while the MP3 is playing).

2. Yes, you can loop based on a start and end position (A-B) within an MP3 or a recording you make. You can set the positions by punching it in real-time, by time value (eg, 2:03 - 2:33) and by measure #. The loop has to be for one second or longer.

3. Not sure about this one -- I just got the unit and haven't played with the rhythm bits yet.