For us, mid-flip, we have not seen this, even on pieces we didn't have formal bids on yet. 

There's no way I'd agree to a flat rate for a consulting engagement as these engagements can range from 15 minutes of questions over email to one or two dozen hours of research and formal presentation. 

By consulting with an attorney either directly or through your property manager, one is also able to enter into a less formal behavioral agreement in the interim.

You don’t want to pay “B+” area prices only to realize after closing that you were on the neighborhood border and your property is actually in a B-/C+.

If I'm wholesaling, I'd offer to JV with them at 50/50.No matter what happened, I would formally thank each of the investors for their help.

He's already balked at giving her back the security deposit, so she's asked me to help her write out a letter to him with a formal demand.

Were the border stones laid down in mortar/cement?

Additionally, when should I then pursue formal pre-approval?

By entering into an agreed Modification BEFORE going delinquent you never have to get to the formal forbearance stage. 

I'm brand new to formal real estate investing but have been long term renting a condo for fifteen years.