Can anyone weigh in on how to find a responsible, affordable property manager for my first property?

Nearly 20-year property manager here.

This is before we account for vacancy, management, capex and maintenance, etc.

These sellers typically want a fast sale to move on with their lives and avoid ongoing conflicts.Relocating SellersPeople who need to relocate for a new job, military deployment, or other personal reasons often seek a quick sale to avoid the burden of managing a long-distance property.Inherited PropertiesHeirs who inherit a property they don't want to maintain or manage may be eager to sell quickly.

Could you recommend a reliable agent and property manager that I can work with to kick start my journey?

Something tells me you won't be working 4,060 hours to do so - 80 hours a week year round.If it is a more active rental model that it is not considered "rental" income, then you would need to put in at least 100 hours with that being more than anyone else (employees, contractors, management company, etc), or you would need to put in at least 500 hours.So your "quick" question is actually fairly complicated. 

What are the consequences if a BnB owner/investor (my client), decides to change hosts or self-manage in the middle of a booking?

If she is, it will work wonderfully.My last piece of advice is to buy a few books and learn to self-manage this one unit.

Consider appreciation as well.There is more to consider, such as how you will manage the property, etc.

I also wanted to start learning about the deal-making and property management processes.