Hi Ahmed,
To answer your questions:
1) You will need to have a deployment (runtime) license for all the machines that you plan on running your application on. However, you will only need a full development license for the computer that you are actually developing the application on. You can see a full explanation of the different types of TestStand license in the document
"When Should I Purchase a License for my TestStand System?"
2) In regards to calling executables, TestStand has a builtin step to call executables making it extremely easy to do. You can download an evaluation copy of TestStand
here to see how easy it is to use as well as see the simple Call Executable Step.
3) In regards to price comparison between TestStand and a customized test application, this really depends on the project. Each project can have a different cost. However, you can take a look at
this cost analysis to get a general idea of
one example of cost comparison. This is just an example and also compares an older version of TestStand.
For more specific information about cost, please contact a sales representative at (888) 280-7645.
Thanks,
Caroline Tipton
Data Management Product Manager
National Instruments