Just recently I realised the problem you are having with the total time marker and with dragging keyframes, I was surprised that neither of those things were doing what I thought they should be doing!
What OS and Browser are you using? Normally we develop in Windows Desktop running Chrome, so the scrollbars are pretty chunky.
I don't think there is an easy workaround for small objects, you can select the instance in the layout by clicking on it's corresponding track in the Timeline Bar, but the changes need to be made on the instance itself, either by modifying it with the various handles or through the Properties bar, that's just how C3 works.
Can you explain what you had in mind for the MoveTo behaviour + Timeline, I am imagining an expression, but please explain.
I'll go look at our error tracking specifically for timeline errors, normally we pay attention to the big offenders and the small ones slip through the cracks.