Dialogs Section:

Show Un-Mounting Dialog — Uncheck this box to prevent the Finder from displaying an annoying dialog box explaining to you that unmounted volumes will reappear when you startup. (A lot of users may never see this dialog box on their systems—so most will not have use for this feature. It mainly shows up when you unmount hard drives or hard drive partitions to the desktop, or use AppDisk, a RAM disk utility.) 
Show Application Substitution Dialog — Uncheck this box to get automatic application substitution. Unchecking the box will remove the dialog box that halts the substitution process.

The default setting for these two check boxes is checked. Personally, I’ve chosen to uncheck the UnMounting Dialog and Application Substitution Dialog checkboxes to get rid of these two very annoying dialog boxes!

Other Window Checkboxes:

Add Quit menu — When checked, adds a Quit Menu to Finder. If not checked, it will remove the Quit Menu if it existed. Default Apple Factory setting is not checked.
ZoomRects  — When checked, zoom rectangles will appear when you open and close windows. When not checked, zoom rectangles will be removed to speed up your Finder. Default Apple Factory setting is checked. Zoom rectangles refer to the animation that the Finder displays when you open folders, documents, and applications. Removing them adds a real zip to your Finder whenever you open or double-click on an  icon.
Megabytes — When checked, Finder displays file size in megabyte units.
Kilobytes — When checked, Finder displays file size in kilobyte units.
The choice between megabytes and kilobytes is purely cosmetic, but many people prefer one over the other. System 6 used kilobytes, while System 7 defaults to megabytes.

Why quit the Finder?

Quitting the Finder has three major advantages:
1) ResEdit hackers will be able to quit the Finder, thus closing it, and allowing them to modify the currently running Finder.
2) You’ll be able to save a small amount of memory by quitting the Finder and using a file launcher like my own QuickFinder (part of the System 7 Companion Pack! that registered users of the System 7 Pack! receive FREE with their registration).
3) You’ll be able to rebuild the desktop file without rebooting your machine. First, quit all open applications. Then, hold down the command and option keys right after selecting Quit from the Quit Menu. The Finder will then ask you if you want to rebuild the desktop.