What you are doing is simple exercise to eliminate waste although explained through a lofty term "process improvement of skill matrix using value stream mapping"
Questionnaires are a method to discover unexpected relationships or to confirm something you have a hunch about. Now you got to ask yourself what is your research objective here. What are you trying to find ? If you are able to frame it then work backwards and design your questionnaire.
Remember you can torture data to speak what you want to hear. But that's where research gets a bad name.
Ideally you should have a process flow map made of the existing process which identifies the tasks, wait times, delays and length of the tasks.
If you have that on paper then it's easier for you to focus on the problem areas such delays, wait times and length of tasks. You can then go ahead and try to address these issues. Now when you are trying to address these issues there might be a potential case of engaging a questionnaire. A word of caution - don't try to have one just for the sake of having one.
Once you have address the problem areas, you may want to come up with a revised process flow map to compare the efficiencies.
Your research could be more dependent on empirical evidences which is an alternate research method of having questionnaires.
Hope this helps.
Here i do not have an existing process with flaws ready on hand. I have to derive the existing process and find flaws, then i also have to suggest methods for improvement. So can I make a descriptive kind of a questionnaire to know the current process and flaws.
http://www.nwlean.net/toolsCD/VSM/4%...20to%20VSM.pdf to understand what is involved in VSM.
I gather you are trying to build a process. But even if you are trying to build one there could be an existing method which is very haphazard. Plot out the process flow map. You might see lot of delays, wait times etc....
But if there isn't an existing method, then you are trying to better something which doesn't exist. Therefore, try to put a process in place. Here you might want to have a qualitative questionnaire as you say descriptive questionnaire. This helps you to understand where the consensus lies and you might want to ideate the process flow and methods engaged. You might want to use the "Delphi technique". Google/Wiki this term to know how you need to employ this technique.
Now when you have a process in place you might want to again bring this process under the scope and see whether there are any room for improvements. Remember you might want to give enough time for the process to settle in, because people take time to come up to speed.