We have 3 categories of surveys: launched/active, in design, and  closed/finished.  You can work on surveys in design as well as launched/active ones.   When you create a survey, it is automatically in design, where you can work on it and preview to test its functionality.  When you are ready to go live,  go to Edit Survey > Publish to launch it.  Once active, you can continue to test it and make changes.  If you test it live, you can always clear your responses before releasing it.  I highly recommended testing both in preview and live :)

Hey Matt.  Please pardon the fact that I completely missed that this quesion was in the “Feature Requests” rather than “WTF”.   I'd need to check with the developers to see if this feature will be included in the next version of SG, which is due out sometime later this year, but it doesn't seem out of the realm of possibility.  It's useful, right? In the mean time, you could create a copy of the live survey to play with…