Thank you for your feedback. Please find my comments below:
Scrolling behavior: We will create a new feature request for this. Scrolling will first change the selection of the view to keep the UI consistent.
Custom DICOM fields: This was possible in very old versions, but the corresponding UI has been removed. Currently, it requires an XML configuration file. This feature may return in the future with the planned hanging protocols functionality (not started yet).
Ruler measurement display: This could be added as an option. In the meantime, selecting an item already displays the relation with a bounding box.
Font size and colors: The relative font size is global and can be adjusted in the Preferences window (there is a bug with the text annotation font). You can define a default color and change the color of one or several graphics by selecting them (with the selection tool or via shortcuts) and using Right-click → Properties .