Not sure I can address every question this morning as schedule presses. But in Aperture, when in Pause, clicking the fast forward/back button advances the video frame by frame, which is as fine as can be achieved in any video app. That can set you up for using the command to create JPEG.
For the trim, let check in a test again, as I normally am using FCPX, and have not done so recently. I have a few times in order to share to Facebook a simple video, however.
Upon checking again, dragging the Trim panel frame seems to be frame by frame, when I move it.
Not sure I have used QT 7 Pro in ML or if works -- never needed to, as always have done that on my Mac Pro in SL or Lion.
to give you an idea, what Quicktime 7 can do: Things that I like about it:
- You can vary playback direction and speed, see the AV controls panel.
- You can opt to display only a selected part of a movie or the full movie. Displaying the selection only will give you finer controls.
The tiny triangles in the bottom scroll bar mark the selection boundaries.
I am a bit hesitant to recommend QuickTime 7 with MacOS X 10.8.4. I am using it a lot, and have occasionally freezes, even on my clean installed system. My main use it to trim clips further, to convert videos to a different format, to split a video into a sequence of frames, or to combine an animation sequence of single frames into a movie.