Hello, There is a site [edited to remove link] now we want to refine it. We found a freelancer, but he wants to work for Git Labs and asks for the code to be posted there. He also said to put the site on Git Hub for work. For the first time I work with this service and I want to clarify:

1. How to do this?
2. Can hosting help this?
3. Is it possible to restrict access to the code to a circle of persons?
4. Will this affect the operation of the site?
5. Is it possible to work here not only with PHP, but also with asp.net core, as we plan to translate this platform?

Sorry for my bad english