They will work within whatever guidelines that party has set for acceptable loans for transfer, so to that end you could research the Freddie/Fannie guidelines.

but i'm wondering if i should have a business set up first?  

Set up your acceptance criteria before talking with anyone/accepting applications.  

Currently, my plan has it set at 4.5% with a whopping $100 processing fee.  

Set the rules and enforce them.  

I'm curious about what others are paying for the service of setting up a 401K and what level of service is provided for that fee. 

Here are some good places to start: http://www.biggerpockets.com/meet- find and connect with other BP members that are in your area.http://www.biggerpockets.com/alerts - Set up keyword alerts to be notified of the topics that interest you.And, of course thehttp://www.biggerpockets.com/forums - ask any question about real estate!

You can also set up keyword alerts to let you know when people are talking about a certain topic on the forum.

Setting up new traps tomorrow.

I very much agree; SFR and multifamily require a different set of knowledge and expertise.