You will have fairly sizable tenant improvement or build out costs with each lease.  

lower the size of your unit and therefore your build cost per unit, your sale price will go down but focus on density and get familiar with zoning and what your city will approve. my best suggestion is to do it in downtown districts where there is unlimited height and unlimited floor area and you can build every square inch of the property and reduce parking because of proximity to transit. property values are higher, rents are higher in downtown markets, there are just too many economies of scale compared to suburban deals.

What all are common items included in closing costs on a wholesale transaction?

I don't have a comprehensive experience  but I tried to find the least costly one for every step for me and applicants/tenants.

Cost to List + Changes to Listing.Can range from $100-$400 for the exact same listing on the MLS.

While that may be true, take into account the total cost to refinance because it's not just rates that have to drop to make it make sense. 

Really I just want to learn how much things cost item-by-item.

I don't think there is any amount of savings that could justify the cost of a total tear down and rebuild.

This strategy allows you to spread out the lead removal costs a bit perhaps not having to remove Lead from two out of three units, and only removing it from the unit where you happen to accept a tenant that has children.  

With $50K, that would be a purchase price of about $250,000 not including closing costs and repairs.