I am new to this. Figuring out how to use it. I am trying to create a custom post by filling out a frontend form. I am using ajax button in the form. This button triggers wp_remote_post().I have the following doubts.

1. I have a front form. can that be used to create a custom post by filling out and that creates the custom post with on the same website?
2. When I visited a website they said header authorization is not safe to use? Is that the case?
3. Username and password added to the header auth. Is it possible to send a request without that?
4. Basically user has to login to fill out the form and so any way to get the username and password to make the request?
5. Can the rest API post request be limited only from that form? Say someone can’t do it from outside?