1. In order to handle both situations, you can make the following change to the suggested code:
list = frm.Controls.Controls.Controls;
list = frm.Controls.Controls;
You can also refer to the attached sample, demonstrating the same.
2. This is in discussion with the developers. I will inform you once there is any information from them.
3. Please note that you can set font for list box items on filter editor form as suggested earlier. This font remains the same for selected/deselected items (as shown in the attached image).
Could you please let me know if you are facing issue with this or is there any other issue?