Boomerang functionality

[jessethom@canada.com]

Can someone please clarify a couple of things about the
Boomerang:

1) Can you hear the initial loop while you are
overdubbing?  For instance, if you started by recording
a drum loop, and then you wanted to overdub a guitar
riff, would you be overdubbing blindly, or are you
essentially playing along to the initial loop?

2) Does the initial loop you create control the
boundaries absolutely?  In other words, if you recorded
drums and you nailed the timing, would you have to nail
the timing for the overdub(s) as well, or are the
boundaries set by the initial loop?

Thanks guys,
-Jesse