1) I believe that it is possible to edit the registry to do this but the easy answer here is to use Tweak UI which is downloadable from http://www.microsoft.com as part of the free Power Toys add-ons. This will allow you to have the computer automatically log on with a username and password. You can still log on with a different username and password by choosing Close all programs and log on as a different user from the Shutdown dialogue box.
2) There is no GUI equivalent for the subst command but it still exists under Windows 95. Subst is good for mapping folders that are on a local drive to a drive letter. If you are using Microsoft Networking you can also use the command net use to map a network share to a drive letter. Using Explorer you can use Map network drive from the Tools menu to map a network resource to a drive letter.
3) The computer really only concerns itself with moving data into the video RAM. A separate mechanism is used to send the appropriate signal to the monitor. The data in video RAM can even change during a refresh. The only consequence of a higher refresh rate might be if the program is attempting to coordinate its video updates with the refresh rate to minimise screen flicker. Normally Windows 3.x or 95 does not do this.
- Roy Chambers

Tweak UI, one of Microsoft's 'Power Toys', lets you create an automatic log on to Windows 95