I don't know the answer for 1), but for 2) I have a possible solution:
If it's getting assigned an IPv6-address by those RAs, it means it is using SLAAC autoconfiguration. For a server, I think a static address is a good idea. Since SLAAC is based on the MAC, this is rather static (unless you change the NIC), but maybe the better idea is to generally configure also a static address for this interface. If you do that (adapter settings), it will still assign itself an SLAAC address, which will then be the default for outgoing connections (which might be unfavorable in regards of PTR-records). So my solution was to disable SLAAC:
netsh interface ipv6 set interface "Ethernet" routerdiscovery=disabled
(change "Ethernet" to the name of your interface, I found this solution here: http://ximalas.info/2014/02/04/disabling-ipv6-autoconfiguration-in-windows-servers/
This of course might be a problem if your prefix changes, but this is a general problem with IPv6 and dynamic prefixes and I haven't found a proper solution (not involving scripts). I guess the configuration-mechanisms in today's software are not programmed yet for those kind of IPv6-issues. For HE-tunnels, the prefix is static though.
Let me know if this is what you were looking for.