(Please ask one question per thread, unless the questions are related to each other.)
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You can change the folder tree's horizontal scrolling behaviour via Preferences / Folder Tree / Options
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Not sure what's going on there. I don't think anyone has reported anything similar, although List mode isn't used by that many people.
Are you using the latest version of Opus? (10.0.4.0, or 10.0.4.1 if you go with the newer beta version.)