By the way, all renewal prices are known for 10 years in advance from the registrar that I use.

It's better to choose companies that are accredited domain registrars, they have the right to make records in the domain registry, you'll be sure that the purchased domain is really registered to you.

Yes this is true. Everything may be similar. But in some points there may be differences. I would advise you to pay attention to fair prices right away. Because there are cheap domain name registrations, but expensive renewals. You can check prices with the Pananames registrar. I chose this option. Everything is immediately clear here.

Who can help understand?

All domain name registrars seem the same to me. Is this really so or are there any significant differences? I want to register multiple domains. Therefore, I do not know how to choose the best option. Or is it all not important?