1. Menu > Configuration > Core Settings > Layout (Tab)
"Panel Tab" section
There is a setting named
[.] Remember split size between restart(*)
There are limits to the splits size it remembers.. 0/100 will not due.. but 25/75 as you ask for should work.
2. Menu > Configuration > Explorer Panel > Dislapy (Tab)
Scroll a bit down and there is a "Folder Tree" section
You got an option there you can disable then it will not expand folder in the tree when selection it
But it will not expand on double click. you have to click the
- to expand and browse in from the filelist for it to autoexpand
3. You can change the default column layout and you can also create Multiple layout that are auto used form different path.
But you can not lock a layout to a panel.
Right click on column header to find all the options for layouts and for creating and changing layout.
(It is also possible to change column sets from script.)