Not everything, no. Or, at least, I haven't experienced anything like that, yet.

I can't say for sure because my tethers and I don't speak about what we feel or experience, but my guess is it's very random and the stronger or more uncontrolled the thought or the feeling is, the more likely it will be felt by the one you're tethered to. and...

You can think of tethers perhaps delivering thoughts and feelings in pulses or waves. I don't usually feel anything from multiple tethers at once unless something chaotic is happening to everyone. And if you ignore them they get weaker. A tether needs to be maintained or strengthen to avoid losing it.