Airport express and airplay 2

Hi

I have extended my wireless network via an express, and have another connected to a speaker. I’ve just bought another to connect to a stereo.

When I scan Wi-Fi via the utility app, there are 6 signals floating around - with another express it will be 8.

3 questions....

1.will all these WiFi signals interfere with each other or cause devices to struggle to remain connected consistently?

2 If I had the 2 streaming expresses set to ‘join a wireless network’ ( not extend) will I still be able to choose to airplay to one or both of them.

3 can I stream to both expresses independently eg laptop iTunes to one, amazon music to another?

Any comments welcome

thanks