:"(died 1286 × 1292)". What does this convention mean? Died some time between those years? 
 :: Yes. 
 :"Previous post: Precentor of Brechin (× 1246)". Isn't it more common to write c. 1246? 
 :: Means sometime different. c. 1246 means around 1246, "× 1246" means in or before 1246.  ()