Multiple synths - how would you do it

The workflow is a bit strange. You do not need to delete anything generally: you can keep gazillions of tracks in the project with no appreciable load on your computer if they are frozen, and just hide them if they are in your way. My understanding is that the freeze is rendered at the full fidelity set in the program, just as if the track is playing live. When you render the track to a wave file on export, you generally lose some of the information that the program uses internally for processing. 
 
edit:
 The bit depth of the freeze is under user control: Edit > Preferences > File - Audio Data, in the Render Bit Depth field.

If I have a project that I want to use 2 different synth sounds from, and the synth is not multi-timbral (can only play 1 sound at a time, whereas multi-timbral is where a synth can play multiple sounds on multiple midi channels at the same time), then I simply insert an additional instance of the synth into the synth rack.
 
So, each instance of FM8, for example, would have a different sound loaded, and would have its own audio track(s).
 
With regard to the midi, if both sounds are to play the same midi data, clone the midi track and point that midi track to the 2nd instance of FM8, and have the audio track(s) for that instance point to the output audio from that 2nd instance, and then both sets of midi tracks will trigger their own FM8 sound, with one sound coming from each instance of FM8 in the synth rack.
 
I hope that the above is understandable - I AM on my very first tiny fledgling coffee, so I don't even know if I am typing in English yet.  :)
 
Bob Bone