blockchain.info transaction timestamps set into the future
1) Are these valid transactions?


Yes


  2) If they are valid, how can I assign a valid timestamp to these
  transactions? Would it be 'fair' to simply assign them the block's
  timestamp? 


You can do anything. Yesterday I've timestamped them as 1905, today as 2048


  3) From what I understand about the Received Time, it represents the
  time that bc.info sees the transaction, so how can this this timestamp
  be occurring? Is it a bug?


Yes.