Hello PhilaNi,
No, you can not have NI-DAQ 6.9.3 and NI-DAQ 7.4 on the same machine. On to your counter question, you will just need to find a pulse train generation example, and go from there. Note: Finite pulse trains take two counters, so if you are already using one counter, you will be limited to doing a continuous pulse train task with the other counter.
-Alan A.