Cues, jumping, current song time...

I using the Javascript M4L API, but I assume my situation would be the same if I were to use api objects instead. Can folks answer, confirm, deny, expand on any of these observations?

In Arrangement view:

1) The function jump_by() moves the current playing position in a relative manner. But it seems to split the current position from the play start position, respectively orange and green triangles, here (if the IMG tags works): I guess you'll have to follow the link.

So while you can jump while playing, it doesn't seem you can jump and then play from where you jumped to? Any way to programmatically move what I call the play start position?

2) In the absence of cue points, it appears that jump_to_prev_cue() and jump_to_next_cue() will move to the beginning of the song and the end of the loop marker. Are there any other ways to move to the boundaries of the loop marker? I know you could add cue points at start and end, anything more elegant?

3) Is there any programmatic way to select the marked loop, equivalent to what shift-command-L does? Related, play_selection() then requires a manual selection to do anything?

Thanks, Charles