Clean the domes will help with the IR issues, At least it does for some of my cameras that get hit with humid weather seeing the rain don't hit them but still look like dots at night if I don't clean them off at least every other month.. Next if the camera is in an area with enough light just turning off the IR can help or turning the camera in Color at night can help until you get your replacements.. Audio is there just very low.. Didn't have a loud mic at the time.. My Mic not much better today lol
Here is an a video I did 4 years ago about the subject