Don't miss Red Rock Crossing (iconic view of Cathedral Rock) which is nearby Red Rock State Park. Also visit Chapel of the Holy Cross (don't have to be religious). Drive up and back through Oak Creek Canyon. (Can do this on route to Grand Canyon) Lots and lots of hiking/walking trails that are easy and you don't have to go too far to feel like you are out in the wilderness on the red rocks. Agree that West Fork is one of the top hikes. It's in Oak Creek Canyon. Get there early, parking lot fills up! Same if you want to go to Slide Rock State Park. Do your walks in the morning (not as hot).
Tlaquepaque Spanish style shopping village is a great place to wander around, if interested. Also, maybe do a Jeep tour.
Some restaurants....Coffee Pot for breakfast, Dahl & DiLuca for fine Italian dining, Elote, Barking Frog, Cowboy Club, Schoolhouse. Look at reviews online.
For Indian Ruins, I suggest Montezuma Castle and Montezuma Well.
A day trip from Sedona to Grand Canyon is nice, but you will probably miss the best times, sunrise and sunset. And I discourage driving back to Sedona in the dark for one unfamiliar with the area. I would try to work out a stay in or near Grand Canyon NP before or after Sedona.