Hello again :)
To your questions:
a) You cannot directly control row height, but there is a new(ish) column options called 'Large previews' which can be enabled for file attribute columns with the display type 'Gallery'.
b) Images in list rows are generally taking up the entire vertical space, they should not need vertical centering. In your screenshot the images (and everything else) is offset from the top due to a behaviour change in webkit browsers (Chromium v144). For some reason (I cannot find anything in the change logs) they changed the way that margins are used in table cells. Since the change has not been announced (as far as I can find at least), we do not know if this is intended behaviour or will be changed back. We decided to wait a short while before patching this, in case it´s a bug in Chromium and will be reversed.