Common fees will include a set-up fee, a leasing fee for each turnover or a lease renewal fee, marking up maintenance, retaining late fees, and more.

Example for multifamily- My 4plex had a tenant in one unit paying $24000 annually of which I achieved $14,000 annually NOI after taxes, insurance, yard work, common area utilities.

What are the most common challenges investors face when securing fix and flip loans, and how do they overcome them?

Examples of common objections include needing to discuss with a spouse, feeling it's not the right time, uncertainty about the location, or having funds tied up in other investments like a 401K, 1031 exchange, or the stock market.

Reliable tenants are the exception, not the norm.A common mistake is assuming that all renters are alike so the property type is not critical.

It's a commonly applied local overlay in the 'usual suspects' of States that have restrictive tenant protections, so its unfortunate that you thought you didn't have to accept it...technically you may not have been required to 'accept the voucher', but you have to allow them the opportunity to apply and then allow the housing office to decline the property. 

And if they are, and you have not sold your property interest, explore common strategies like 1031 exchanges.

Fairly common.

Quote from @Shane Bishop: Software is a common question on BiggerPockets.

You may need to pay a broker to help consult with you through the deal process, but they commonly know lenders that will finance their type of deals, they clearly know the acquisition process from LOI to contract negotiations.