[TREmp77]

The two different answer screens is quite normal. One is when your phone screen is off and locked (the slide to answer screen) and one is when your phone is awake (the answer buttons screen). However both should work without fail, well mostly without fail. I have some problems with the end call button after a phone call.
My slide to answer screen is actually better for mine, it works all the time. So maybe a reset or just go into boot loader and wipe cache and davlik a couple times, that way you wont lose any settings.