1 & 2: Go to Folder Options, then choose Save > For This Folder.
3: Font size changes made using Ctrl+MouseWheel are only temporary and are not part of folder format. The default font size can be changed via Preferences, but there's no built-in way to save different font sizes for different folders.
You could use a script add-in to set the fontsize to different values for different paths, however. Event: Trigger Flat View (or any other command) in configured folders is a good starting point, or may even be all you need if you only need one font size in addition to the default.
Set FONTSCALE=125 or similar is the command to configure the script to run. (That would set the font size to 125% of the default font when entering folders in the script's config list.)
If you click the window icon (top-left), Customize is one of the menu items in there, in case you have closed all your toolbars and cannot access it another way. You can turn the toolbars back on from there.
I want to set all music folders to Filename - Album - Artist - track - Year. So I go to Folder - Folder Formats - Manage Folder Formats - Content Type Formats then double click on Music and set the fields like I want them. Then I click Music as the content type then Apply and OK and sure enough, folder is just like I want. Then I click Folder and Folder Options then Save for This Folder and All Subfolders and OK. Then I close the folder and reopen, and its back to the same original default music format.
Now here is the strange part. If I DON'T close the folder but reboot, it boots with the folder I am working on displayed (which I don't want but think I know how to fix) then I close it and reopen, and back to the same original default music format.