the activity rings is super addicting. I disabled the Breathe notifications as they're completely worthless. you'll love the activity rings tho... it definitely helped me lose weight and want to get the rings closed. you can set your weekly move goal and keep increasing as you go.
I dont really use any special apps other than hole19 for golf. I use the activity app for my cycling and after I open my strava app and it says apple workout ready, its great.
I got a really nice leather band that I wear sparingly but mostly just wear the default band. i'm sure you cant go wrong on any band you find.