Once the trace is set, the deadlock graph will show up in the ERRORLOG file. ( -> when it happens)

The second error looks to be more related to Sharepoint. There are a lot of posts out there dealing with a divide by zero + error 15070 (http://darrylclark.blogspot.com/2010/01/event-id-10036-divide-by-zero-error.html). As I said, you may consider posting these errors on Sharepoint forums like http://www.sharepointforum.com/en-US/Pages/default.aspx or http://social.msdn.microsoft.com/Forums/en/category/sharepoint/[/url].

David B.