As far as touches the question of how to spend a lot on a card and still have a low utilization, let's take your Discover as an example. It has a 2k credit limit. First make a reasonable guess as to how much you'd spend on it on average if the CL wasn't a consideration. For example, maybe you'd like to spend $2000 a month on it. In that case set up four automated "push" payments from your checking account through billpay, each for $450. If your statement prints (for example) somewhere between the 2nd and 5th of the month, then set up a payment on the 6th, 13th, 20th, and 27th. You'll find that you'll end up having a negative balance every once in a great while, but mostly you'll end up with a statement balance of around $200. And if you want it to be very low but still positive, pay the balance to $5 on the 1st.
