I also suggest reconsidering plans for a Linux server, as maintaining a Linux server on the internet is much simpler and cost effective than a Windows server.
For #3, it would be good to have this capability in the regular viewer as well, for those of us with static clients (host installed) as well as occasional clients (who are using the quick agent).
I am getting the same, for the same file, when extracting the portable version. However, switching BitDefender out of auto mode revealed that BitDefender was indeed locking the file.
I have seen behavior that backs up Ashley's experience, tho I am able to remote in. In my case, I'm using the public server, and see that every few minutes (seconds in some cases) where a host will flicker offline and online again. Noticed this due to having notifications enabled. Using Internet-ID connections, host is a VM on my machine. No changes to the connection's settings besides adding the connection/host to my address book via internet-id and setting the password.