Routing for External Effects

I want to incorporate some external effects into my Cubase Pro 9.5 setup, and am wondering what the best way is to configure the ins/outs so that I can use each effect in different ways, according to what is needed in the project. I have a pair of Warm EQP-WA’s, a Drawmer 1968 MKII compressor (with 2 channels, and the ability to link each for stereo operation), and a Lexicon PCM92 (with stereo channels, and the ability to set up different in/out routings from within the unit).

For example, if I want to use the Drawmer on a mono vocal channel, would I set it up with a mono in/out from my interface? And if I want to use the Drawmer on the master bus, as a stereo in/out? And could I save each of these configurations as a Favourite, to quickly swap between them? I have an Apollo Firewire interface, with eight analogue ins/outs available, and have the external effects connected on channels 3-8. Thanks!