Fediverse

I joined the fediverse like 2 weeks ago. I'm trying to find the answers to all my doubts reading discussions around, watching videos etc, but there are still some questions I'm looking an answer for. Here they are:

1. Is having a own hosted server a suggested practice? I could see some benefits, like not having to worry about which instance to join or having the full control of your own account. Furthermore, it's maybe more "professional"? Like @myname@mycustomdomain is maybe better than @[email protected] ? I don't know, I'm asking.

2. What are the server costs to keep an instance alive? I know it depends on the amount of users and -I think- the bandwidth used, but what's a common range of the costs per year, just to have a rough idea? (Like 50/100€ per year?)

3. What managing an instance involves? I'm not talking about a self hosted instance now, I'm referring to a medium/big instance with many users and communities. I'm asking this question to better comprehend what are the difficulties the owner/owners of an instance may face and so what could make them shut down the instance in the long term.

4. What happens exactly to an account when the instance in which it is registered shuts down? Is the account lost? It can still be migrated to a different instance?

5. What exactly change in my user experience if I decide to migrate to a different instance? I potentially see less contents? It just changes the posts I see in the "local" page?