It would be a huge time saver to make the time "line" actively chase the end point dragging of events, so you can tell precisely where the event is compared to other tracks above and below.
Is this possible?
I don't think it's possible in Vegas to move the "timeline" line (cursor) along with your edit.
You can, however, set the cursor directly to where you want your event to end by just clicking to that position. Then drag your event to the cursor and let it snap magnetically to it.
This way you dont have to manually set and delete any markers.
I don't know Vegas specifically, but does it have any kind of mark feature? The traditional solution to this is to apply 3 point edit techniques and scrub to set your points.
If you aren't familiar with 3 point editing, it consists of determining 3 out of 4 points, the beginning of your edit on the source, the end of your edit on the source, the beginning of your clip that you are bringing in and the end of the clip you are bringing in. If you know 3 of these, you can determine the forth and complete your edit.
For example, with a subtitle, I would scrub the source video to find the start and end point of the subtitle. I would place a marker at each of those frames and would then add the subtitle between the two markers. This general technique should work with just about any reasonable editor and it sounds like it will address your workflow problem.