Sorry, I don't have a full answer, but the following suggestions: The -trace option requests the debug MPI library, which might be helpful when you wish to debug. You might be able to get the same effect by setting LD_PRELOAD to the mpidbg library. Failure to find the trace .so calls into question your installation and mpivars setting for LD_LIBRARY_PATH, but may not stop you from proceeding.
Please do not use -trace and -gdb option together. -trace option is used to collect information about MPI communications in your program. Once you get a trace file you can analyze it in Intel Trace Analyzer (traceanalyzer). Of cause you need to have this product. If you use -trace together with -gdb your trace files will be useless. Also trace library inserts own functions, so debugging of such application will be useless as well.