One of the major driving factors for increased premiums is the carrier's requirement for higher replacement cost limits on file for buildings. 

Condos are less expensive to buy, but you have condo fees and special assessments and condo rules.

Each closing, whether multi-family or single family, is going to have some of the same costs: title insurance, attorney fees, inspection fees, appraisal fees, fees associated with financing, etc.

Yearly bank fees for each, aka choose your bank wisely.

This is bad math, once most people factor in their income tax bracket. 

As others have said, the location is a big factor in MTRs, but so is the clientele you are going after.

There are a number of factors for why a property could be on the market a while.

The PM fee is meaningless, 

Experienced managers can help evaluate potential investments by providing insights on rental demand, market rents, tenant preferences, and location-specific factors that affect leasing success.For example, rental properties need to be close to conveniences like major roads, shopping, and schools.

Offer discounts for applying in a short time period or- offer a free application fee.