Mr M2Dude sir !!,
As far as for ships and power stations, well a turbojet is always going to be favourite, as all the gas energy is contained in the jet efflux; this can be efficiently transferred to the load in question by a gearbox coupled to the HP spool.
Not quite right here I'm afraid. There are some designs which are coupled to the HP Spool - look up GE LM6000 for that but the majority of installations use the jet efflux to drive a separate (in a mechanical sense) Power Turbine which can be then either coupled to a gearbox or directly coupled to the load and run at a set speed as in power generation - i.e. 3000 or 3600 RPM for the frequency depending on which country. All the controls I've worked on govern the speed of this Power Turbine and the Gas Turbine, often called Gas Producer or Gas Generator, ramps up or down as required. Just being monitored to ensure it is operated within it's limits.
All Olympus installations are like this; ships prime movers, pumps, gas compressors, power generation all the same.
regards
Howie