Hi Gminorcoles. I just want to add to Ilias’ answer above. If all you require is a midi sequencer, i.e. dispatching midi messages according to a timeline, Elk would probably be overkill for your needs. Though if you want to output (or input) CV/Gate in sync with the midi messages in order to build a hardware sequencer box, then I’d say that Elk is a good fit for your needs. Even thought there’s plenty of hw resources to do audio processing as well.
At the moment, Sushi, the plugin host in Elk does not really have a timeline. It has a concept of tempo, time signatures and bars, but that’s about it. The reason is that we see it most being used in a live context rather than as a full fledged recording tool.
I think your best bet would be to either roll your own sequencer, or take an existing sequencer software with more andvanced timeline features like the tracktion engine mentioned above, wrap it in a plugin and load that plugin in Sushi. The plugin would then get timing information (tempo, position, start/stop) from Sushi itself. From the plugin you could then output midi messages, cv and gate information and Elk would make sure that it all is tightly synchronised.
Funny you mention Fluidsynth 
we have already wrapped the Soundfont player part of Fluidsynth in a plugin and made that work in Elk. See this thread. I don’t know much about the midi playing part of Fluidsynth, but my guess it that it could be a good place to start.