I don't know of a specific questionnaire that is readily available online. But you here are some resources you might find helpful to go through to get an idea of what you will want to ask the client to get the information you need for setting up a Facebook page or a Twitter account. There really are some key points to consider so that you set up a page or a Twitter account that are optimized to help them get found but also for branding purposes and as part of their overall social media plan and presence.
Build Your Presence on Facebook: Get Started in 5 Easy Steps
Facebook Pages Manual
If you go through these guides, then you will get an idea of what information you need to set up a Facebook page.
Here is a post that just came out today on CopyBlogger that includes tons of Twitter resources- The Ultimate Guide to Twitter Marketing
. It's total information overload, but the first section on Setting Up a Twitter Account will likely have some info and resources you'll find helpful. The key thing with setting up a Twitter account is picking a good username as well as optimizing the profile bio with keyword rich content.