2) You mentioned the property is old ... could it be eligible for historic tax credits?

One-foot overhang for eaves would be allowed.ADU Size (in sf)LOT SIZE (SF)ADU MAXIMUM SIZE (SF)3,000 - 5,4446005,445 - 9,0007009,001 - 10,00080010,001 - Up900LOT SIZE (SF)ADU MAXIMUM SIZE (SF)Up to 90001,0009,000 and greater1,200Number of Bedrooms and BathroomsTwo bedrooms allowed on lots with an area greater than 9,000 square feet, and only one bathroom.Up to two bedrooms and two bathrooms allowed for all units.Attached ADU Maximum Floor AreaMay not exceed 50% of the existing or proposed primary dwelling living area.May not exceed 50% of the existing or proposed primary dwelling living area or 800 square feet, whichever is greater.Design StandardsVisual compatibility with existing primary dwelling is required.No design standards, except new simplified standards for attached ADU units for historic buildings listed in the Historic Resources Inventory.Parking requirementsAn ADU requires 1 space unless the property qualifies for an exemption under State law—see the parking requirements.If a garage has been converted, the main dwelling parking space must be replaced, as uncovered or in front or side setback areas.

Historically anything in my life that has been worth a damn has had its fair share of obstacles to overcome.

I was buying court house steps in fort Meyers  new or near new homes for 30 to 40k cash at the steps in 093. my well documented clients in PHX AZ losing 4 plexs they paid 350k for in 05 and having them go vacant and they let them go to foreclosure thereby ruining their credit and losing whatever cash they had in them.. 2010 they were selling for 100k or less and still vacant.so on and so forth.As long as credit does not freeze the values have been reset .. those that were lucky or smart enough or came of age to be investors and bought in the trough historic low price points historic low interest  many paid cash as financing was still tough.. so as long as they don't drink the cool aid and refi out and leverage up you have the makings of a very strong asset base.. plus all the foreigners who paid cash there were literally hundreds of thousands of homes paid for in cash by Off shore folks.. then add in the half a million or more that were bought by hedge funds.. 

Experienced real estate agents and investors in an area know of the things that can impact the usability of a comp that less experienced people will often miss - (e.g. if there is a "historic" district within a 1 mile radius which would make using a comp from that area less useful even though it is within a mile) Having someone who does not have a financial interest in whether or not a deal gets funded review the property is a way to help pull emotion out of a deal.Also, we don't send evaluators out to review a deal (thus having the borrower incur an evaluation fee) without reviewing the deal with them before.

Really loved the historical homes we've seen driving through neighborhoods.

One reason I don't predict a major crash again well a few.. and why I think fence sitters may get a sore butt.is that so many of the NEW crop of landlords are better prepared than pre 08  they have more money into the deals they are far more educated.. the turn key business is far more mature and reliable than pre 08... so that helps those markets. financing has been locked in at historic lows 5 % and under long term money is ridiculously good.. also this crop of landlords had the best buying seasons ever coming out of 08 to 2011.. so asset values were reset to under replacement values and under by a long shot in some markets.. 

I have done that already, and in short I came to following high level findings.Positive impact on appreciation: -area was historically undesirable due to association with “East Austin” demographic stereotype, but that his changed rapidly in last 10 years due to proximity to downtown, universities, corporations moving in, redevelopment of parks/recreations etc.

I plan to go for value add with immediate cash flow, but my biggest concern is that a large portion of homes in my town are very old (we have a large historic district). 

Tourism is an historic well established business there and make a comparison Mexico Vs Colombia is like compare a tropical island vs a desert .