New to E-prime Programming, Help with Syntax Meaning?

[Reed Maxwell]

Hi, all! Glad to find this forum. I'm new to E-prime, but I'm familiar with SAS and (to a much more limited extent) R, so programming isn't entirely Greek to me. I have my handy E-Primer (Spape et al.), but I'm still a bit lost regarding some of the syntax's meaning(s). Maybe you all can help me.

For example, I have the following syntax . . . 

VARIABLE = myObject.InputMasks.Responses.Count

and later . . . 

keypressResponse = CKeyboardResponseData (_myObject.InputMasks.Responses(VARIABLE))

Questions: 

1. My understanding is that a data type conversion is taking place, here. Is this correct, and if so, what is the direction of the conversion?

2. What is the purpose of the underscore (i.e., '(_' ) in the syntax?

3. Why is 'VARIABLE' in parentheses?

Any help is much appreciated!