Questions about my Macbook air CPU

I have been playing video games on my Mac for about 2 years now. But only is it recently that I notice my mac heating up on playing some games that do not usually cause my mac to heat up, the performance on my mac stays the same, but it heats up on certain activities that didn't used to. here are a few questions i'd like to ask about this.

CPU: Intel core i5 1.8 GHz

Do CPUs degrade? (specifically the CPU on my MacBook air 2017) Does it decline in performance over the years just like how a battery degrades over time? or does it only degrade through dust build-up that prevents cooling? If it does degrade, how long does an average CPU last?

Does playing games or CPU intensive tasks cause internal damage due to the heat? (for example: playing Roblox which makes my mac heat up and fan sounds) Does the heat cause damage to certain parts of the laptop, like the battery?

For my MacBook Air 2017, what are some signs my mac is overheating?

Detailed answers is highly appreciated :)