Hi Phil
Animating out is going to be as easy or as difficult as the template demands. There isn't really any 'best practice'. As someone who makes FCP templates and plugins for the living, the only 'best practice' I follow is to always to plan the build in and out at the same time, so that I do not animate myself into a dead end.
In this case - if you ramp in, then use ramp to animate out. You can apply a second ramp to manage that.
For the overshoot behavior - it is not so simple. The overshoot does not have a built in reverse function and it needs to be managed differently to get a true reversal.
Check out this tutorial for that https://www.youtube.com/watch?v=XJtzOviiGUY
However, keep in mind, that overshooting animations often look silly on the reverse. I hardly ever reverse an overshoot, i prefer to add some manual keyframes instead.
Now, about the duration and the timing.
If you want to be able to extend the 'pause' between the build in and the build out, then that is what those markers are for. I see you have them set up in your project. Build in and build out markers will allow you to extend the duration between the in and the out animations in FCP. If your build out animation is going to be the same timing as the build in, then be sure to animate correctly at the other end of the project. If the animation if 1 second, then start animating 1 second from the end - whereby the last frame of the animation is the last frame, or second to last frame of the project.
While we are here, can you please attend to all those previous posts that have been left unattended and unresolved? It helps others who may search for similar questions later on. Thanks.