No matter where you choose to invest, please keep in mind the following (copy & paste):--------------------------------------------------------------------------------------Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a Class A property in Class D area, what quality of tenant will you get?

How do they pay?

Are there any red flags or challenges specific to this neighborhood that I should keep in mind?

A strong partnership is built on trust, shared values, and aligned goals, so it's not something to rush into.I recommend attending in-person networking events to meet like-minded individuals.

The E-Myth by Michael Gerber- Start and operate your business with the consumer in mind... not you... not your product or service.

$500,000 after taxes is likely close to $325,000(maybe more or maybe less).Assuming cash-flow from rentals is offset by depreciation, you would need $325,000 of annual cash-flow from the rentals.If you can get $200 / door / monthYou would need 135 doorsYou can work on this type of math to figure out how much rentals you need.Be mindful that rentals require some type of work.

If so does this mean I would pay the impact fees on 2 separate occasions when each pair of building permits are pulled (even though all 4 units are on one parcel) or do I have to pay for all 4 at once? 

Even with house hacking with a lower down payment (which I am not sure would work if I get a studio size condo), I would still need to pay more out of pocket than what I would pay renting (I can get rent by splitting a studio with a friend for about $1200/month).

You also need about 20-30% down on land loans so keep that in mind!

I think there are two maybe 3 ways to look at this in my mind.  1) you go into it and bring it all up to modern standards but using that old charm to basically take what is there bring it up to modern standards and rent it out essentially I'm thinking cocktail bar or something trendy like that.2) most banks are on really good centrally located real estate if this is true, then I'd consider it for the dirt, plan to scrape the lot and go vertical with whatever the highest and best use is.3) a kind of combo of the two, if the lot is in a good location and its doable, pull the vaults or other "character pieces" out of the building, scrape the lot, and build whatever is best suited for the site there, but incorporate those historical pieces into the final designs.Is the site near a major retail area?