The easy answer to the GUI is MainLobby and the MLHSPlugin. This very quickly brings Homeseer to having the best user interface in the business - bar none. It will cost you something like $100 more for it, but if a GUI is important, and you believe it will be the center of your total system - then it's a no brainer IMHO.
You will also find that MainLobby Server has the ability for additional hardware and software 2 way control plugins - like a 2 way Generic Serial plugin so that you can send out and recieve serial commands. This data can then be sent on to Homeseer.
You will also find that MainLobby Server has the ability for additional hardware and software 2 way control plugins - like a 2 way Generic Serial plugin so that you can send out and recieve serial commands. This data can then be sent on to Homeseer.