I wouldn’t presume anything ever “has” to be done, that actually limits you from seeing all the other options. I never use the transition trick and make transitions all the time. I record the elements of my jams like drums, bass, guitar, vocals, synth melodies, into separate buffers. Those buffers are available to the entire project and I just bring any one or multiple ones in when I want to…
Sorry if my responses might make the situation seem more confusing as I answer a question with “well, you don’t have to do that and there’s a bunch of other ways to go”. But that’s how the OT is… If I were you I’d focus on setting some of those ideas up one at a time and working with them, figure out how to move between them later and make modifications if needed. The more time you spend with OT the more these things will become apparent.
You already have some nice ideas there of how you want your OT to work, I’d start by picking one and working with it until you’ve nailed it. One step at a time, each step you learn things along the way that makes the next step easier.