The claims of up to two months with an hour of reading a day are marketing. A lot depends on how you use the device, the number of screen refreshes during usage, and whether wifi is active or not. If you're getting 1 1/2 months, that's not particularly bad. How long are those 2-3 sessions per week? Is wifi on or off?
I've seen the yellow-at-100% with a number of devices. I wouldn't worry about it if you're seeing that kind of battery life. The little software gauge on Android devices is notoriously inaccurate, so don't expect it to be exactly in sync with the charging circuitry. I'd go by the light.
If you read the tech forums for some phones, a common technique is to charge to 100%, power off the device and put it back on the charger to get longer battery life. It's a bit like squeezing a bit more gas into your tank at the pump. That extra bit might gain you that extra weekly session or two.
