Does block size effect Miner's Hashing speed?
Only block header gets hashed, and it has fixed size, so the total block size doesn't matter.

From Wiki:Block hashing algorithm


  The body of the block contains the transactions. These are hashed only
  indirectly through the Merkle root. Because transactions aren't hashed
  directly, hashing a block with 1 transaction takes exactly the same
  amount of effort as hashing a block with 10,000 transactions.