In a crash, it is normal for ceramic filters to become damaged. Severe impact can cause considerable damage to the internal components of a receiver. High levels of vibration that are allowed to get to a receiver are also a cause of damage to electronic components. That's why a receiver should have about 1/2" of foam rubber around it that's not compressed.

When you mix two channels, there will be some delay between them. It's because the channels are processed in order by the transmitter. Channel 1 gets done first, then channel 2, then 3, and so on. There is enough of a time differential between channels 2 and 7 that you can notice it. It's normal for almost all R/C systems. The new Futaba 14MZ has different processing which makes the delay very much minimized.