When buying an older property when to upgrade components

[Randy Dulac]

I am looking at a 2 family that poses to have some good potential cash flow.  I seem to be getting hung up on the level of upgrades necessary.  The electrical panel is listed as fuses.  I have to assume the entire electrical system needs to be upgraded or does it?  When would you upgrade an electrical system?  A plumbing system?  I have attached a picture of the property.  The siding is asbestos.  When should that be upgraded?  The rest of the properties on the street are in better overall appearance and condition.