Looks great!

Recipe isn’t too exact but that should be fine. Output looks delicious!

% is usually related to weight. I’m not totally sure this way of calculating is right so if I’m off someone please let me know.

My understanding is it’s easier to use grams for weighing out your loaf. Assume 1000g flour (big loaf). Add 100g starter but we kind of ignore that, it’s effect is negligible. Add 700g water. Now you’re approximately 70% hydration.

Can’t help on the yogurt add in, I’m interested in that but haven’t ever done it or looked up recipes using it.

You should. Making sourdough is fun. Even mistakes usually taste good. If you need any hints or tips I’m sure you’ll find help here.