1) How can I make a 2 second custom placeholder? When I drag it out from the Solid Backgrounds bin it's always 10 seconds and I have to change the duration to 2 seconds. Is there a way to make one that is 2 seconds long so I can just use that one when I need it instead of having to change duration all of the time?
2) Is there an audio placeholder? When I drag my Solid Background from the bin onto the timeline I have to move it downward towards the audio until it buts up against it. I would like to just be able to add it to the timeline next to the audio clip.
1) Do an insert or overwrite, or connect edit from the generator browser. Mark in and out in your Project with a 2 second range and hit q, w, or, d.
1b) Or, simply hit q, select the 10 second generator, hit control-d and type 2, period. That will change the duration to 2 seconds quickly.
1c) I don't know if your custom placeholder is a motion template, but you can change the duration of the template so that it is 2 seconds. If you are using Apple supplied ones, you can open a copy of those in Motion.
2) If it's a video generator, see above, otherwise, not sure what an audio placeholder is. If the audio is in a secondary storyline, you can select the shelf and add a video generator to it., otherwise X is going to treat it as a video clip and put it above the primary if you choose to connect it.