I've done one of those, and yes some brokers work at multiple branches. They are semi-targeted, you need to tell the MSC who you made the appointment with after the initial visit. My guess the reason they have so many of these is rotation - You can only do one every 6 months. Other than that, is very straight forward, you don't need to get your credit run (just say you're just starting to look whether you can afford it or not), and if you go for it, have a good backstory as to where are you looking to buy the home, what your salary is, what your credit is (again, you don't need to run it, but you can say your credit is excellent or is so so, or you can come up with a credit score). If you're already a customer of BofA they may verify your details in the system, but once again, they don't need to run your credit report (I can't emphasize that enough times because I think that's what scares most shoppers from this one).
In my particular case they did see an old mortgage I had once with them and some of my other accounts I had with them in the past, but really the focus was on my current situation for the shop.
Also be ready to write a moderately long narrative and scan a ton of paper.