For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

Agent fee's etc. for cost of selling is a drop in the bucket compared to the returns. 

Situation 2: You are paying for your brokers fee:In this situation the seller has declined to pay for a buyers broker fee.

Quote from @Briley Roe:  yes those fees are very high as you have a broker fee and other fees for a loan little over $100k at 6+ points. 

No fees, no pre-pay.

Like deferred maintenance, (bad roof, worn out water heater/AC Unit, warped flooring, water damage) etc, unpaid utilities,  unpaid taxes, a second loan, unpaid HOA fees, a bad pool, bad reputation, sometimes squatters, sometimes they were drug houses, and so on.

@Andreas Mathews admirable, but make sure you do some research so you understand what a PM can make.Starting your own PMC business will require 75-150 doors to make a decent living, depending on gross rents and your fee structre.Working for a SFR PMC as a PM, will require a RE license and you usually get paid a percentage of the gross rents the portfolio of owners/properties you manage generates.

If I add up all the lender fees and my holding costs—like points, origination fees, and interest —I can figure out how much profit I’ll make and what my maximum offer should be.

Costs will seem high relative to the loan amount on these smaller loans, $5-6k in lender fees isn't uncommon. 

Property manager (PM) 's lawyer continued the case to get the unpaid rent from the tenant.PMA between landlord and property manager(PM) has also expired so landlord got the property back , but when landlord requested to settle the account and the deposit( there is one month deposit from landlord also), PM refuses since the lawsuit is going on with the tenant, Additionally PM is still charging the monthly property management fees from landlord even though landlord is managing the property.Landlord is done dealing with PM and requested the PM to withdraw the lawsuit against the tenant ( landlord is aware that he will loose 2 months rent), PM came back saying they cannot withdraw the lawsuit since that will violate fair housing law.QUESTION:Does withdrawing unpaid rent case against the tenant violate fair housing law ?