Fixing this may cause plumbing issues like the engineer said due to drainage issues or cracking the pipes when the house move back to level breaking the seal at the joints.  

This would be a fee for building, elec, plumbing ext. $67.00 per permit.

Do you know how to fix plumbing issues, install new locks, install ceiling fans, stuff like that?    

I guesstimate approximately $35K to $45K to completely redo the roof, replace and repair the dry rotted base house frame sitting on the foundation (sills, floor joists and subfloor), outside brick repair, new drive ways and electrical and plumbing updates.The average selling price for well-maintained and updated duplexes similar in design in the area are $85K to $105K.

I would bet there is some middle ground of having to tear up some walls so show plumbing and electrical is done correctly.

So I did the insulation work and the dry wall and I'm going to do all the trim and i learned how to wire in some lights and plugs, I learned about plumbing and all sorts of things.

Even the best maintained properties have systems (like plumbing) that are probably original and are at the end of their useful lifecycle.  

(whaddya know...)International Plumbing Code and Sections 703.6 of Appendix J in the Georgia Amendments.International Mechanical Code.International Fuel Gas Code.National Electrical Code.International Energy Conservation Code.International Fire Code.---------------------------- also from the DeKalb County website:Manufacturer's installation instructions for residential installation.

I have experience with HVAC, general Remodeling and Renovation of houses, electrical and plumbing basics and general handyman work.All the way up to this point in life I feel like everything is pointing me in the direction of Real Estate Investing.

If you're in this for the long term and are not accounting for eventual replacement of the roof, HVAC, plumbing, paint, floors, carpet, hot water heater,appliances, foundation/framing, landscaping etc, etc, etc, SURPRISE, this things will wear out.