Ok, a couple of points... First, to be nitpicky, 27% + 22% is not "more than half". :-)
Second, from briefly browsing their website, the Liberty Fund is either Conservative Republican or Libertarian (I'm guessing the latter), so take that into account when judging anything they say. That's not to say that they can't be trusted, but be sure to consider their biases.
But regardless of the groups biases, the survey still shows that 49% agreed at least partially with the statement "Taken as a whole, government policies of the New Deal served to lengthen and deepen the Great Depression," right? That's one way to look at it, another is that 73% of economists either completely disagreed with the statement, or disagreed "with provisos". A perfect example of how changing the words just a little bit can pretty dramatically change the apparent meaning of a statement.
So the next question... Can the survey itself even be trusted? If the survey wording or something else was wrong with it, than it's numbers are meaningless anyway. Unfortunately, the survey falls pretty flat on this point. As it is worded, anyone who has even the slightest disagreement with the opposite statement ("Taken as a whole, government policies of the New Deal served to shorten the Great Depression") would automatically be lumped in with the people who appear to think the New Deal lengthened it. There should have been a fourth option "disagree with provisos" to get a better understanding of where people lean.
Going in to debt during a budget crisis is never an ideal solution, but sometimes you have no choice. Have you ever been unemployed, and had your car break down? You have two choices, fix it by putting the repair on your credit card, or don't fix it, but not be able to make your job interview next week. Unfortunately, sometimes the axiom "desperate times call for desperate measures" is correct. The same is true for the national economy in this case.
You are correct that if we did nothing, the economy would most likely eventually recover on it's own. But if we did nothing, things would get FAR worse before they got better. You're right, much of what has been done has been bad, but remember, the Republicans get a big chunk of that blame. For example, they were the ones who insisted on business tax cuts that will have almost no short term economic benefit (something like $1.03 return on every $1.00 spent), but forced the removal of increases to the food stamp programs when those are shown to have just about the largest return on investment of all possible stimulus methods (something like $1.83 per $1). Had the Republicans put aside their ideology and actually allowed a real stimulus plan to pass instead of the watered down travesty that we have, we would almost certainly be in much better shape today.