@anuradigital
If you are redirecting users after they register, it will also redirect the prospective vendors after they register.
When admin approves a pending vendor- one method of approval will send an email, the other will not send an email notification:
1.) Email: wp-admin > users > pending vendors > hover over vendor and click Approve. Email fires.
2.) No email: wp-admin > users > edit user > change role to vendor, update. No email.