I does get a high responce but it also puts a lot of prospects on guard.

Helena is an older demographic and the economy is stable due to state and federal government, county government, VA hospital, and the National Guard at Fort Harrison. 

Is anybody familiar with building code requirements relating to window guards/stops in small multifamily buildings in Philadelphia?  

Most strong tenants want to have at least a 1-year lease because it guards against this very scenario (changing the rent in 6 months).

Also, home depot carries a product called 'red guard'. 4 coats of that stuff and it's like a layer of vinyl underneath the tile.

As the Coast Guard motto says; "Semper Paratus"-always prepared.all cash

So be careful, keep your guard up by following up, verifying, and researching.

I'm going to assume you want income rather than hanging about with negative cash-flow properties for appreciation potential.Class D properties offer the best cashflow but they simply don't suit the  lifestyle and aptitudes of most investors who don't want to deal with constant drama, theft,  and repairs and collecting rent checks physically, on some fraction of your properties that pay accompanied by armed security guards.  

I was thinking I'd have someone I trust stay in the house during the rehab, to "guard" the place.

I'm in no rush, as you say, since prices are still in the doghouse here in Florida, but I don't want to be caught off guard when the market finally hits bottom.