I am living in my family's almost 100 year old house. Part is still on a fuse box and the newer part is on a normal electrical box. The electrical wiring is very old. What would be involved in switching out the fuse box for a new box, and what about the wiring?

This needs to be seen.

May I suggest that you call several licensed electricians and get estimates for the work.

For example, we have no idea on the accessibility of the old wiring. Is the old wiring know and tube, cloth covered?

Can you send in some pictures?