Terminals is a secure, multi tab terminal services/remote desktop client. It uses Terminal Services ActiveX Client (mstscax.dll). The project started from the need of controlling multiple connections simultaneously. It is a complete replacement for the mstsc.exe (Terminal Services) client. This is official source moved from Codeplex.
Depends, what do you mean by "host server". It depends on protocol you use to connect to the remote machine. All plugins are configured to use common protocol port by default (e.g. 22 for ssh).
Can you please advise which ports need to open on the host server>
Thanks