Writing the Contract:**It's highly advisable to consult with a real estate attorney who can draft a comprehensive contract that outlines all the terms and conditions of the seller financing arrangement.

If you're unsure about the legalities or the best approach, consulting with a property management company familiar with local laws or a real estate attorney could be invaluable.Best of luck with your new property and navigating this transition smoothly!

Who is the appropriate professional that I would need to consult about legal aspects and benefits of moving my rentals into LLC?

Those tax returns are due by June 15th of each year and you should consult with your tax professional.W-8ECI Form remains in effect for a period starting on the date the form is signed and ending on the last day of the third succeeding calendar year, unless a change in circumstances makes any of the information on the form incorrect.

Definitely consult your attorney on this one

That said I would definitely consult with both a lawyer and a CPA before making a decision. 

The laws there can be much different then we are use to in the US, so you should consult a local attorney.

You're likely better served by a CPA that does have that focus and understanding.There are several such CPAs here on Bigger Pockets, so best best would be to reach out to some of them, schedule a consultation and see which one would work best for you.Best of luck! 

Please consult with your own legal and tax advisors for your specific situation :) Here are some points about my experience: I looked around the internet and spoke to a few different vendors that offer this service, most of whom were referred to on BP.

Do a thorough market research and consult with local real estate professionals.Good luck!