I am glad you brought this up. It just so happens that there is an exhibit just opening today at the Southwestern Baptist Theological Seminary,not far from were I live, displaying some of the fragments that have been held in a private collection for several years,but now being made known to the public. You asked why they are so important to Protestants? Well I have inserted a link that my answer some of those questions. http://bpnews.net/BPnews.asp?ID=38150
In regards to the Canon of Scripture,Protestants will view the Dead Sea Scrolls much like they do Early Church History,they will pick and choose what they want to believe. Much of the reason they reject the Catholic/Orthodox Canon,is primarily because many of the original texts where not composed in Hebrew,and they use various sources such as Jerome,and others as a buttress to uphold their objections,particularly the anti-christian Jewish Council of Jamnia's rejection of the Apocryphal works,but If both they and Jerome had access to the Scrolls,the outcome might have been much different.