If they don't live there or are mean neighbors then you send it certified mail and submit the certification after 30 days if there is no reply. 

My biggest concern is the flood certificate says the main floor of the property is 3.7 feet above Base Flood Elevation.

Curious as to how I should sign in Part II "Certification" where it says "signature of U.S. person".  

Partly, this was due to the ease with which tenants can get certificates that legally bind many property owners to allow certain types of pets.

They listed me as Certificate Holder. 

• Short term rental of one's own primary residence only• Not able to rent a room or primary residence for more than 120 days a year, or apply for extended home-sharing• Extended home-sharing would be granted if additional criteria are met (see above)• Possession of a Transient Occupancy (Tax) Registration Certificate from Office of Finance• Not located in a unit subject to the Rent Stabilization Ordinance (RSO)• Approval from landlord (if a tenant)• Home-Sharing takes place in area approved for residential useHere is the document - https://planning.lacity.org/or...I would give them a call and see what they say.

In Chicago, many times on the MLS there is a garden or attic apartment listed as a 3rd unit on the listing, but when the zoning certificate comes back from the city, it will only specify two units.

As far as I know, you will have to allow the city to inspect any unit you plan on renting once every 3 years or with any change in occupancy to obtain a certificate of habitability, as described here: https://ecode360.com/4243371This registration requirement is indeed new.

Legally you can't ask for proof of certification - When it is not obvious what service an animal provides, only limited inquiries are allowed.

I'm looking at the protocol to register and then have the safety and lead risk inspections, fix any issues and ultimately get the certificate of compliance for 3 years, then repeat.