This recipe is my daughter's favorite. When growing up, I didn't have it with peanuts, but have started adding to give it a little protein boost.
You may add vegetables such as carrots, peas, beans. If so, cook them partially along with the onions, and add maybe a quarter cup of water extra for the veggies. I like mine with just the onions and the chilies and have not tried with vegetables.
I have also seen variations with ginger garlic paste, and the dish made almost like a biryani/pulao, but I like the simple vanilla version for this dish!
Preroasted or not:
I never buy pre-roasted rava or semiya as I would like to control how much and what kind of oil I use, for one; for another, I'm never sure of the shelf life of something that's been cooked in oil. And, it hardly takes any extra time to roast it at home while making the upma fresh.