What additional ingredients and steps to take to make fast cooking oatmeal from oats?
I use large flake oats. Two-to-one by volume tap water to oats in a bowl. Don't even stir, you'll have to do something with the wet spoon if you do. Handful of dried raisins and/or cranberries. Microwave for 2 minutes at 70%. Add a few shakes of salt (salt is really important for oatmeal) and give it a good stir. When you take it out of the microwave it will look done, but stirring will reveal there are less cooked oats under the ones at the top.

Give it another 2 minutes at 70 and stir it well again. I often stir in a little milk at this point, which can cool it as well as making it creamier. If you find you would like it sweeter, a little brown sugar or maple syrup over the top and not stirred in work wonderfully.

If instead of large flake you have quick oats, you'll need less time in the microwave. Instant oats need only boiling water, but they generally only come pre-flavoured and sweetened. If you did get plain instant, you'd probably want to cut your dried fruit small so it would be ok with just boiling water. Steel cut oats need significant cooking - most people I know use a slow cooker over night. If you're not sure what you got from the bulk store, either experiment with different cooking times until you're happy, or look for pictures of various oat forms until you know what you have.