We are aware of the layout conflicts and hope to address that in a big layout change in the future.
The HD signal is something that used to be used but doesn't do much anymore. It will be removed soon. The RC strength indicator does change. The new aircraft have to be really far away for it to drop even a little bit. This is a good thing!
DJI has added a lot of behind the scenes logging and it has started eating away at the CPU available to apps. That is the likely cause for the video breakup. Make sure that most other apps are closed and disable the Image Footprint setting to free up some CPU. They are both A8 processors but the iPad must be busier doing something else.
If you stop the aircraft before it reaches the first waypoint there will likely be issues.
You can get away with a bit less overlap than usual in steep terrain since the downhill side will cover pretty far down the hill. We always recommend at least 75/75 for anything that you care about.
In the future, please post different topics as different questions to keep the search results relevant.