http://www.intel.com/support/network/adapter/pro100/sb/CS-030612.htm has the answers you are looking for.
E10G42BTDA and E10G42BFSR
are the same except that one ships without optical modules (BTDA) and one has SR optical modules installed (BFSR). Both adapters can use E10GSFPSR.
E10G41BFSR has one port and E10G42BFSR has two ports. Both adapters can use E10GSFPSR.
I hope this helps.