I would say that my advice will greatly depend on your goals and what resources you have to invest with (time, money, skills). 

What questions should I be asking the insurance agent to understand what they are offering and what to add / remove from the policy?

Both banks and credit unions are good starting points, as they can offer different types of financing solutions that might suit your down payment goal of 15-20%, but the chances of getting 15-20% are limited as 25% is more likely to open more doors for you. 

Most lenders will offer two options:1: 20% down and 20 yr amortization and 10 yr term.2. 25% down and 25 yr amortization and 10 year term.Rates will vary by region, lender, and relationship with your lender.  

Determining whether the venture falls under a service or rental business hinges on the provision of substantial services; for instance, if a bed and breakfast service is offered, it must be reported on Schedule C, triggering a 15.3% self-employment tax.Moreover, personal use plays a crucial role in the classification of the property.

Do you mind to share any resources (or another lawyer contact), where I can learn about these stuff and what structure is the best for now to stay as anonymous as possible while keeping your funds safe?

While house hacking can offer immediate benefits in terms of offsetting housing costs, it's crucial to also think about long-term goals and how this investment fits into your overall wealth-building and real estate portfolio growth strategies.Good luck!

So, back to making an offer...

Most lenders will do a hard credit pull before presenting a formalized term sheet, but that is after a property is under contract and your offer is accepted/you submit a full application and send in a credit authorization. 20% down with no STR experience is pretty normal on the market, but you will likely be using a haircut AirDNA projection instead of the full 100% to qualify you. 

Would love to connect with someone that could offer some guidance.