FMOD Studio has no destructive editing capabilities at this time, so we generally recommend trimming your audio files in a linear audio editor such as Protools or Live. It is possible to set a sound module to start part of the way through its associated audio file by adjusting the “Start Offset” knob located in the “Seek” section of the module’s Trigger Behaviour Drawer. However, as the effect of this property is always calculated in real time, it consumes some of your game’s resource budget. We therefore recommend that you only use Start Offset if you need the amount of trim to dynamically adjust.
FMOD Studio provides a number of ways of determining when and how a sound ends. I cannot tell you which would be best for your project without knowing exactly what effect you are trying to achieve.
I’m afraid I don’t understand your last question. Are you asking how to use a second audio file to conceal the point at which a looping sound begins again? If so, you can achieve what you want by using a combination of a loop region and a non-timelocked sound module to play the second file.