1. You can select an individual VM to back up. Here is a bit more info on this > Creating VeeamZIP Files for VMware vSphere VMs
3. Yes, that's possible. By default, VeeamZIP job uses VMware Tools Quiescence, but you can also use pre-freeze and post-thaw scripts executed by VMware Tools.
<...>In the working area, select the VM(s) and click VeeamZIP <...>
<...>By default, Veeam Backup & Replication uses native Microsoft Hyper-V quiescing mechanisms to create a transactionally consistent image of VMs<...>