Now, according to the vacant building registration department, our permit will expire in a little over a week from now, on 7/17—three whole months early. 

Reg D (Particularly 506(c)) is the exemption from registration that most funds like ours use, but it has strict rules on who you can take money from (accredited/qualified investors).

3) As the unit does technically have it's own address, will it be a problem if the subtenant uses that address for legal registration?

Also said that there needs to be a business registration application and a transient occupancy tax permit application.

One of the problem is that it looks costly (100$ to set up each LCC and 50$ per year registration fee on each LLC).

Some cities require registration plus high fees or taxes.2.

For example, licensing and registration requirements are ambiguous, making it difficult for regulators to intervene.

This means that you will probably need to pay registration and filing fees in at least 2 states if you don’t buy CA property as a CA resident.Any lawsuits should be limited to the assets of the LLC and not your personal assets (assuming you run the LLC appropriately and the corporate veil is not pierced, some debate as to SMLLC).

there is a registration with the city when you have a tenant.

Look for the registration and find the last owner . get them to get you a title .