ssr123456

My maxima has a little over 90,000 miles and I'm going to take it in for service. Does anyone know which belts are the important ones to replace and which are important just to check? I'm hearing a high pitched noise that I believe is coming from a belt that's to the front and left of the engine near the bottom of the car as I'm looking down on it. Does anyone know what belt this is? Thanks.

ssr123456

Also, are the heater hoses and radiator hoses something I need to check out? I don't see anything about them in the manual or things I'm reading, but I saw it on an auto repair site.