I would first check city/county STR rules and HOA (if applicable). 

You could front the down payment as well as monthly payments to the seller, then charge interest on them.

Quote from @Ashish Acharya: @Sanjai Dayal If your LLC owns the commercial building and leases space to your medical practice LLC, it’s essential to charge rent at fair market value (FMV) to avoid IRS scrutiny.

My knowledge is free, but I am most happy to charge for it, if someone is willing to pay!  

The first applicant made $4000/month.

They say they charge 10%, but that doesn't include finding new tenants, renewals, upcharge for maintenance, etc.

I have no idea how real these rates are they dont have credit score just A+,B+ , C+ d and e and application fee is $400.

Generally, most reputable lenders in this space won't have any significant surprises with terms and fees because they spell them out upfront in the applications that they provide before you move forward with the loan underwriting.5. 

(Hint - go on VRBO and see what your local competition is charging). 2) How much do you intend to put down?

And, yes, there are years of data points to validate that just within my office, tens of thousands of dollars of wasted appraisal and inspection fees for deals (mostly not mine, thankfully) that had 0.00% of going anywhere but the "Loan Application Declined" bin.