1. Not familiar with the Wahoo app, but if you’re getting a watch, then you shouldn’t need it anymore. One thing though, you need to use a chest strap with your watch. Optical (wrist) monitors are crap.
2. Yes, delete/remove all of the Training Peaks auto-thresholds. Also, disable the settings for automatic changes to thresholds and notifications thereof.
…am in pretty good shape, at least I think I am.
3. The early weeks of a training plan are more important than the latter. I would reduce the number of harder weeks before cutting transition or base weeks (regardless of fitness level).