Can Packer connect to a VM in vSphere via SSH?

Question

I'm just getting started with configuring a VM on VMware vSphere and I'm using HashiCorp Packer to create the VM template. I'm very pleased with how most things are working out for me, but I have a couple of questions regarding how Packer connects to the virtual machine, and I'm hoping that someone over here can help me.

I am using the vsphere-iso builder from the VMWare vSphere plugin.

1. Is the ssh_password field required? Things seems to fail when I don't set it, but it says nowhere that it is required (as it says for ssh_username, for example).
2. I read here about the ssh_clear_authorized_keys that "If true, Packer will attempt to remove its temporary key from ~/.ssh/authorized_keys and /root/.ssh/authorized_keys". What temporary key? Is that used for authentication during provisioning? What on earth is ssh_password for then?