To answer your first question about shedding: "I want to know what to look for when I am".
Well, you may begin to see a lot more than 5-10 in the shower. What about outside of the shower as well? You should consider this, too. Are you finding hairs everywhere?
For me... I've been using propecia for 16 years and, while it's maintained much of my hair, I still shed for several months. My bathroom floor and bedroom quickly become littered with fallen hairs of various length and thickness. I lose about 20 or so hairs in the shower every day. When i towel dry, another 5-10 fall out. When I comb... same thing. Then I also have random hairs that fall onto my shirt, pillow, wherever. The point I'm trying to make is, when you are shedding, you will see hairs falling/accumulating in many more places than the shower. It will be noticeable.
The one main difference I would say between my first shed and every shed thereafter, is that with my first shed, hairs were not being replaced... which sent me into a panic. However, at the 3-4 month mark after that first shed, density began to pick up. This gave me hope and confidence that my treatment was working. Thankfully it was.
I'm not sure how long you've been on your regimen, but stay at it consistently (this is key) for 3 months and evaluate. As for minoxidil, I have only brief experience. I stopped using minoxidil after about 2 months because my system was too sensitive (e.g., increased heart rate, headache were my side effects). On the other hand, propecia (finasteride) I've used pretty much non-stop for 16 years (missed only 4 days) with 2% ketoconazole shampoo every once in a blue moon.
Best of luck!