I've advised clients  with multi-families that if you show the bank that you are majority owner (articles of incorporation) they will likely acquiesce to the change. 

In Cambridge it's $2,269,563.Single family homes are normally what gets discussed as that's what the majority of  sales are. 

The vast majority of my bookings are on Airbnb and I made the amateur move of paying the flat fee to Homeaway when I signed up.

In Florida the AC is running 49 weeks out of the year and for the majority of the time you’re home and want the temp to be comfortable.

I have read that these type of properties are sold through networking, however I’m new to this (never sold a property before).The asking price is on the range of €2M and it is visible here: www.ninfale.comIdeally, I would invest part of the profit in small rental real estates in major European capitals.What advice would you give to someone in my place?

As far as the 203k itself goes, they are a great product, however they can be a nightmare if you don't have all your ducks lined up. 

My idea for a more sustainable future would be to get a job at major CRE firm brokerage in a junior role.

they require a low 1.0 debt coverage ratio so as long as your rents cover PITIA expenses then your good to go, cash out is required to be used for "business purposes" only their retail division is Cash Call mortgage, FICO can be as low as 600 and cash out LTV's from 65-75% based on credit, I used to work for IMPAC as they were rolling out the product, it is pretty competitive in the market for this type of financing. 

After that it plateaus and cash flow is the majority of your wealth creation.

If you are trying to use the "Delayed Financing" exception a couple of things you should keep in mind, #1 you must have paid all cash for the property (no borrowed funds for purchase) and no liens on the property #2 you can use the maximum LTV allowed for purchase of property (ie. for an owner occupied property 97/95% LTV or non-owner occupied max is usually 80-85% LTV) #3 must refi within 6 months of purchasing the property (so for the most part you are going to use the purchase price plus improvements rather than the new appraised value) #4 property will have to qualify condition wise within the lenders guidelines, so no major work should be outstanding like broken windows, holes in the roof, ect.