A knife is not a saw. One should try to cut down and forward, away from you. And you should slightly protrude your knuckles out so that your knife is away from your fingers as it is against your knuckles.
IMO: If you're going that small, get a food processor.
Food processors are very useful in a number of recipes: homemade cuts of ground beef (ever try Rib-eye burgers?), breadcrumbs, casserole?
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Similarly, if you're julienne (aka: french cut) a lot, consider a mandoline slicer. A knife can be used, but dedicated tools are faster and more efficient.
The knife is the general purpose cutter. But there are many other cutting tools that are better at making certain shapes.
I would recommend a (curved) chef's knife for most people, though.
Do all your measuring of ingredients at once. Once all of the ingredients are measured, then combining them when needed becomes far more efficient, instead of context-switching.
Alternatively, use a scale. Keep your dish you're baking on the scale, and just keep adding stuff until the right amount of weight is added. IMO, the scale methodology is far easier.
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As far as "chopping an onion", there's a safe way to slice food. You want the knife to be very sharp, then when you do a slight "slicing" motion, you can feel the bite. When you feel the bite, that's when you can press down, knowing that the knife won't slip on the onion and slice off a chunk of your skin.
If you push down before you feel the bite, you may have the top of the knife slide off the top off the onion and onto your fingers. With a dull knife, that's not a big deal (but a dull knife means you're not really going to be cutting very quickly...)