I have a old house that has knob and tube wiring in the attic that I need replaced before I insulate it.

These are all questions whose answers will help you chart the way forward ... there is no one size fits all answer.From an operational perspective it is always pleasant to know that your building envelope is relatively efficient (insulated and air sealed); that building systems (electrical, plumbing, HVAC and communications are up-to-date and dependable) and that you have the ability to put accountability for resource consumption in the hands of the tenants.  

In addition to how you work the roof line, you also have to be aware of how you are going to do the insulation and venting. 

I have no clue on insulation, windows, fire alarm, CO detector, fire retardant door thickness.

Some are even building HUD homes with 2x6 exterior walls, radiant barrier roof decking, a full house moisture barrier, low-e vinyl windows, extra roof/wall/floor insulation and high efficiency HVAC systems.

Structurally the house looks sound will need all new insulation, electric, plumbing, and probably plumbing.  

I stuffed the old vent full of rock wool insulation and covered the end with plastic as we explained the differences to expect to the tenant.  

In theory the banks want that twenty percent down so that they are insulated in the case of a foreclosure. 2.  

.$2,000 demo, permit fee and miscellaneous items.This is just a quick run down and like I said price will vary if you want to gut the whole place because at that point you have to add insulation etc.Hope this is helpful. 

If you looking for someone to quarterback a project and insulate you from the day to day nuisances of renovations it would be good.