Hi there,
1. I think most of the issues you are encountering are related to the wall geometry not being in a component, so please make sure that the walls are in a component. Not in a group! And that the cutting components are placed outside of the wall component, and not on bear geometry.
If you need to convert a group, that already has wall cutters on it, follow the 3 step workflow of:
Remove Cuts > Convert the group to a component > Refresh.
You can read more about the various situations where you would need the 3 steps:
https://flextools.cc/learn/wall-cutter/#Advanced-Operations
2. Make sure all the wall face normals are facing out, i.e. if you change the model's style to 'Monochrome' all white faces should face outwards ,and colored faces should face inwards.
3. It could be that because the wall was a group (If I'm not mistaken), some unwanted lines were created on the bottom of the wall. Those can interfere with punching the opening through when placing the door all the way on the bottom. If after converting to a component you still have issues with a specific wall, it could be some of the lines are divided and hard to find. Best to recreate the wall in that area and refresh the component so it punches a new opening.
When the wall is a component, it should work a lot better, without extra lines being left behind or other unexpected behaviors that you mentioned above of sometimes cutting and sometimes not.
If you still encounter issues, please send us the model and we'll gladly take a look.
4. Regarding having open doors on one layer and closed doors on another, I understand the benefit and we will try to integrate an option for that in future releases.
Currently, the solution is to select all the doors (you can also select components that contain doors, or select non-doors indiscriminately, or even select the entire model) and run the 'Open-Close' tool. It will open (or close) all the doors in one click.