Hi Fabrizio - welcome to the forum! I'm a second year home beekeeper in Pennsylvania USA. I have a Flow frame setup and am starting two new colonies this spring.
The only part of your post I can try to help with is
Many experienced beekeepers around the world regard the Flow system with doubt, and have tried to discourage new beekeepers from trying it. But there are many open-minded experienced beekeepers too, quite a few on this forum. It's too bad your local expert seems to have a negative attitude. The Flow frames are really just a different way to extract honey, and all the rest of the things a beekeeper does would be the same as with any other type of hive. If you can persuade him/her to advise you on all the other important aspects of beekeeping, and look to this forum for tips on using the Flow system to harvest honey, you could definitely be successful as a home beekeeper.