Inspection Report Concession Recommendations?

[Wendy Stclair]

Im stuck! Its my first time buying a non-turnkey property and the inspection report has many things that are giving me pause. Looking for advice - i'm told the seller will entertain whatever requests I have. The market is Savannah, houses are selling fast, this one has been on market for 90 days. Its a 1925 bungalow converted to a duplex - sort of! Price is good for a duplex and rents are stable but the house is marketed for double what the neighbor homes (all SFH) would sell for.

Inspection report challenges as follows... 
While the foundation and most of the wood work seems fine, there are a number of "old house issues" 

- HVAC is not separated by unit at all -only 1 controller in 1 unit,  and HVAC and AC units are 16 years old. 
- only 1 Electric service panel with 100 amp svce - some unapproved attic splicing done it appears
- roof 15 years old
- water supply and drain waste piping uses old galvanized water piping that is subject to leakage (drain pipe is actually leaking to crawl space!) 
- all windows are painted shut  

I will likely ask for some sort of concession or replacement for all of these items, and was thinking at least for HVAC it would be better do on my own terms rather than his choice. Are there things that are standards here i should be aware of? Like is a duplex really a duplex if you haven't separated the HVAC or electrical in any way?  Are there codes i can site where things are NOT up to code that the seller must do?

Any gotchyas? Thoughts? Is this just a mess? thanks much!