Can an H1B visa holder change employers, and what is the process for transferring the visa?

Yep, an H-1B visa holder can change employers. To transfer the visa, the new employer needs to file a new H-1B petition for you. You can start working for them as soon as the petition is filed, but make sure to wait for approval before making it official.

yes, i believe. New employer would file new H-1B petition