Improve file-info visibility in Finder's preview pane
Solution 1:
Sadly, I don't think there is the level of customization in the Finder that you want.
There are "Finder alternatives", like Path Finder, which may lay out information in a better way.
The default size of a Finder window can be set as follows:
1. Close all windows.
2. Open a window and make it the size you want.
3. Close it. Now all new windows will be the same size.
(Since Classic MacOS days!)
Solution 2:
Finder has multiple views including ‘List’ view mode. Your required information can be shown in multiple columns.
Finder > View > as List ⌘2
