Takami,
For number 1, the option in VMware Tools... I would check this box, but this is really the LAST step. If you do this before setting the hosts to sync time correctly, then your VMs will have the wrong date/time.
For number 2, you can setup to sync with either. Like I said, typically, I setup the hosts to sync with a domain controller (or two) and have the domain controller(s) sync with an internet time source. This way, Only the DCs are going to the internet and only the hosts are looking to the DCs for time updates.
Setting the option for #1 reduces the network traffic of the VMs asking the DC's or Microsoft for time updates.
The article I posted earlier on Best Practices is very helpful.