Regardless of whether your task is called with named parameters, positional parameters or boolean flags, you'll access them the same way: via the standard CFML arguments scope. An exception will be thrown if required parameters are not passed, and the defaults you configured will also work just like you expect.
If the parameters were escaped when typed into the command line, you will receive the final unescaped version in your task.
Users can pass named or positional parameters that aren't declared, and they will come through the arguments scope. Named parameters will be accessable as arguments.name, and positional parameters as arguments[ 1 ], arguments.[ 2 ], etc.
If your task accepts a file or folder path from the user, you'll want to resolve that path before you use it. To do this, use the fileSystemUtil object that is available to all tasks via the BaseTask class. The method resolvePath() will make the file system path canonical and absolute. This ensures you have a fully qualified path to work with even if a user might passed a folder relative to their current working directory passed something like ../../.
If you run that task and pass a full file path such as C:\sandbox\testSite, you would get that exact same path back as the output.
However, if you changed the interactive shell to the C:\sandbox directory and then ran the task with testsite as the input, the relative path would now still resolve to C:\sandbox\testSite.
If, from the same directory, you passed testsite/foo/bar/../../, you would still get C:\sandbox\testSite as the path.