If you try to run an import with one or more "ask at runtime" mappings in the import definition, you should get a message that tells you what -mappingproperty parameters are required.
Setting the version the script uses dynamically sounds like a scripting question, and I guess the answer depends where the value will be coming from, and whether you're using a shell shell or a Windows batch file - if the latter then you can prompt the user for a value using something like "set /P version=Enter version", then use the %version% variable later in your command line.
