Sub Interfaces in Frame Relay networks.

I have a couple of questions:

1) I know that Sub-Interfaces in the Frame relay network are used to overcome the limitations caused because of split horizon. But am still not convinced as to how can a software division of a physical port make it act like to differrent interfaces. Am i correct or incorrect. If i am correct can any one suggest some good resource to study more about the same.

2) I also wanted to know about Frame-relay encapsulation. When we specify this encapsulation on the serial port we have 2 options to specify it as the default "Cisco" type or the other "ietf" type.

Hostname(config)#interface serial 0
Hostname(config-if)# encapsulation frame-relay {cisco|ietf}

Now once at this point when we specify the encapsulation type as cisco.
Why do we have to seperately specify the LMI type from one of the 3 choices cisco, ansi, or itu

Hostname(config-if)#frame-relay lmi-type {ansi | cisco | q933a}

I mean is the LMI type not part of the encapsulation type. SO when u selected the encapsulation type as say "cisco" in the beginning why do you need to select the LMI type seperately ??

3) This is a rather generic question. Do i have any place on the net where i can get good simulators even if i have to purchase them. I amd getting the Boson Netsim Simulator, and the Network Visualizer 3.0 for 1000/- should i go ahead and buy it ?

Regards,