It's a rather harsh agent, but I use tarnex. It'll have those pennies shining within seconds. Rinse with hot water, then dry completely.
We always use 1982 and earlier pennies (100% copper).
There are over 350 pennies at WDW, and they do not change those designs too often.
The quarter press designs are changed with each celebration, or about every 2 years. They will usually have a theme, and almost every quarter press will be changed near the same time at the start of the celebration (100 years of magic, 50 years celebration, ect..).
Also, we use pre 1965 washington quarters (90% silver), they run about $1.25 per coin. Be warned that these coins do not press as perfectly as the modern nickle/copper quarters, and there will be some imperfections.
If you become an obsessive collector, expect to spend $200 per year to keep up. It can get out of hand quickly!!
One final note. The coin holders that Disney sells are nice, but the rubberized plastic used in them can promote oxidation of the copper in the coins. They will begin to turn green. We use those folding cardborad/plastic coin collecting holders. The half dollar size fits well for pressed pennies.
Wow, I need help!!
