Indoor camera night vision, clicking noise?

1) The indoor camera night vision does not work. I checked in the camera settings and NV is on.

What's your question here? If it's not working you should call support.

2) in home mode (while sleeping) we hear clicking I think from the camera. when I turn SS off clicking stopped.

Still no question here. Is this the indoor Simplicam? If so, it sounds like you have the privacy shutter enabled which definitely generates a very audible "click" as it opens and closes. The shutter also opens and closes for many events so depending on what's going on in your house the shutter may be opening and close regularly.

3) Is there a way to make the keypad chirp louder when you trigger the alarm, entering the home?

I don't believe you can adjust the keypad volume, no. You can only adjust the volume of the base station.

4) when not paying for full monitoring. Is there a way to just have SS notify me via the app and not trigger the siren?

We need more details here but yes, you can set some things to trigger only a push notification and not an audible alarm or siren. Some things will always generate an audible alarm or siren and that can't be disabled.