Answer 1. 15 M basically.
Answer 2. It can be as much as  the maximum line impidance of cable should not exceed 2500pF.(RS232 E)

The Current_User key holds the data about the user-specific configuration settings of the system, including color, keyboard, desktop, and start settings. The values in the Current_User key reflect those established by the user who is currently logged on to the system. If a different user logs on, the contents of the Users key are moved into the Current_User key.

The Dyn_Data key works with the branch of the Local_Machine key that holds PnP dynamic status information for various system devices including current status and problems.

The Current_Config key works with the Local_Machine branch containing current information about hardware devices.

The contents of the Windows 9x Registry are located in two files: USER. AT and SYSTEM. AT.

When troubleshooting a remote printer, check to see whether the printer is connected to the system through a print-sharing device. If so, connect the printer directly to the system, and try it. It is not good practice to use laser printers with these types of devices. A better arrangement is to install, or just use, an LPT2 port to attach an additional printer to the system. Beyond two printers, it would be better to use network-capable printers.