[Crosspost] Questions regarding Phase and how RF carries Data

I've been studying the CCNA Wireless recently and there are some questions I have that don't appear to be covered by the video and book. It may be unnecessary to know for the book but I'd rather know it.

Can two waves be in phase with different amplitudes? If I understand phase correctly, its when the 0 degree, 90 degree credt, 180 degree baseline, 270 degree trough, and 360 degree baseline all occur at the same time.

If two waves have the same phase, what exactly does that mean for the wave? What if their amplitudes are the same? Different?

Also, curious of what portion of a measurable wave is actually converted to binary.