Hello,
FluidSynth follows the MIDI Tuning Standard in regards to SYSEX command data. I'm not real familiar with this myself, but a quick search on the Internet for "MIDI Tuning Sysex" should bring up some useful info.
As far as setting chorus and reverb parameters parameters (beyond just the send value), there currently isn't anything in FluidSynth to support this. I believe there has been talk in the past about adding FluidSynth specific Sysex or RPN commands for things like this. It may be interesting to even add the ability to run arbitrary commands using Sysex and the usual FluidSynth shell syntax (just occurred to me while writing this). Some thought about security is probably in order though. I don't think there are any dangerous commands that could be embedded in a MIDI file at the moment (such as deleting files or what not - deserves some analysis), but if there were any bugs in this code, it may be possible for someone to craft data to exploit it. At any rate, perhaps the option could be left disabled by default.
Best regards,
Element