The first number that came up in my head was $15k and a new fence.If I can't subdivide I will keep house and add 1800 sq ft addition and house should be in $680k to 700k max.

Despite the "common hearsay" aluminium wiring can be safe, provided the correct receptacles/fixtures are used, or the ends of runs were properly pigtailed to copper.You definitely want breakers over fuses and you would want to confirm the existing circuits have the capacity to handle today's electrical loads and that there is additional room in each unit's panel.

In addition, I am not sure the mail laws, but I might believe that I cannot pick up or hold someone's mail that isn't mine.What do you guys do in these cases?

I would leave the overgrowth and trim it, add it into the landscaping and fix/clean the flooring.  

People moved in with parents or took on additional roommates lowering the demand but there were so many empty bank owned units that the supply was also down. 

Owners, acting in their own individual capacity, are allowed to clean, given this, how can I add additional owners w limited rights?

As an example, let's say the person is about to go to foreclosure because they got behind in their payments due to a job loss for 4 months, but have now found employment, but can't get the back payments caught up.  

Additionally, the 1 place is paid off so I didn't have any real urgency.  

I spoke to 3 lenders today and all insist on me using my own name and transferring after closing which is yet additional fees.

Which is close to round enough, in turn, that it makes me think the lender just documented $10m/yr and stopped documenting additional income at that point because it would serve no purpose.