Old House Needs Work

[Ryan D]

I am a first time buyer with 2 general questions. The house for it's age (built in 1915) is in great shape but needs a couple things: 1. Roof vents. 2. The drain in the basement needs replaced. 3. Everywhere has been rewired except for the 3 bedrooms & bathroom upstairs where there is still knob & tube wiring. Does anyone know roughly how much these things might cost? Just a ballpark estimate? Also, is the knob & tube upstairs something of serious concern?