2. Wifi transmitters eventually degrade and fail. They should be replaced every few years. [It could also be your laptop's wifi transmitter/receiver failing if you only have a single wifi device.]
No, they don't.
Look at your microwave, it's a high powered 2.4GHz radio frequency transmitter. Basically the same thing as a Wi-Fi signal boosted up to ungodly levels. Do you have to replace it every few years because it eventually degrades and fails? No. And if you do, your microwave sucked to begin with.
However, components do age over time and environmental factors can also contribute to degraded signals. But if the former is causing failure at such a short timespan, then again, it probably sucked to begin with.