For example, you can set it to require a 30-night mininum, but: -If there is a oprhaned gap of 29 days or less, allow booking for 21 nights.

Check with local contractors but I suspect a 2” to 3” pipe is required. 

Who’s had success with wraparound mortgages, and what pitfalls should others avoid?

The IRS requires continuity of ownership, meaning the entity that sells the old property must also acquire the new one.

Avoid creating a spousal LLC unless advised by your attorney or CPA, since it can require a separate partnership return.

Some Zoning Rules have minimum square foot required, or have limit of one unit per lot. 

They require less paperwork than a standard commercial loan and afford many benefits on 1-4 unit properties.

Commerical is a bit tougher based on property types but in most ccases 45 days shouls be the normal turn time, unless its a $20M Hotel that has issues with occupancy, Reserve account requirements, legal pedning issues and more.Hard money is quick and fast and can close in a 7-10 days with the right investor and fast up front 'Complete" application. 

Avoid dangerous activities: let one tenant mow the lawn on a multi (multifamily)8.)

My required payments were $235.