Re: time code display / keyboard shortcuts

1. Best way to display source time code on timeline (I want to see
the in and out points for the clips I'm using)

You can see the in/out timecode on the thumbnails on the timeline.
Options>Preferences>Video
Show source frame numbers on event thumbnails as (select Timecode)

4. Shortcut to matchframe from timeline (load source footage of
timeline event with in/out selected in trimmer). I can't actually
find any way to do this, keyboard shortcut or not.

Simple, map the TrackView.Event.OpeninTrimmer to any key you like on the keyboard. I chose the Esc key as that works perfectly for me. Want to matchframe? With the timeline in focus anywhere you leave the cursor you can matchframe the clip to the trimmer by hitting (in my case) the Esc key. If you select a region on the timeline and hit the Esc key it will matchframe the in and out point in the trimmer. Works perfectly.

5. Shortcut to clear / unmark In and Out points.

There is no way that I know of to clear in/out points but if they are not selected (highlighted) they are not in effect so it is as if they have been cleared. If you must remove them, you can always drag the yellow out point until it meets up with the yellow in point and you will now only have a single mark.