@Akzariel Pi 3 has WiFi and Bluetooth built-in. No need for an adapter.
For a microphone, I used this:
For speakers, I just used the speakers built in to the TV, and routed audio out through the HDMI connections.
I don’t have an opinion on PIR vs. IR, but I used a PIR and it was initially a pain in the butt to get working, but once I did it has been rock solid. I used this one:
My biggest problem was I got the two tuning screws mixed up, so when I though I was adjusting sensitivity, I was actually adjusting the timeout. These things seldom come with proper documentation, so you’ll just need to tinker with it until it works.