Let's say proposal A was closed. I avidly followed proposal A and wanted it to succeed, but it didn't so I decide to restart it as proposal B. Since proposal A and B are extremely similar, can I take example questions from proposal A and post them in B?
Sure, there's nothing inherently wrong with re-posting great example questions, if you feel they represent the site well.
But consider the reason behind the closure, too. If folks didn't find the first proposal too interesting (or if the purpose was controversial, or not clear, etc), you may not want to revive the same content for a second iteration. But in many cases, proposals are closed simply because the audience was not available at the time. If you feel there is renewed interest for a relaunched proposal, re-posting great questions shouldn't pose a problem.