Hi,
Sorry - I was using "old" terminology. It's not called auto drop anymore; it's called auto punch. I agree the implementation for setting the in and out points is a bit clumsy. If you option click in the wrong area of the bar ruler, it's easy to unintentionally create a marker.
Yes, that icon with the up/down arrows is the auto punch button. But there are a different set of locators that you need to set for using auto punch, separate from the regular locators used for cycle mode.
When you customize the transport bar, you need to enable the display setting for "sample rate or punch locators". It will display the sample rate until the auto punch function is made active; at which point the display switches to displaying the auto punch locators.
So, once you engage auto punch mode, you can adjust the in/out points from there. And all of this will be independent of cycle mode.
There are also various key commands and optional transport buttons for setting punch in/out points by play head or rounded play head.
All ot this is a bit cumbersome. You can just use the marquee swipe method and be done with it - and not have to worry about any of this. Just make a marquee selection in the track you want to punch in on, and that will automatically set your in/out punch locators and get you ready for auto punch mode when you hit record.
As far as setting a punch in point with no punch out point, your best bet is to use the punch on the fly option.
HTH!