Question about changing drive belt - what else to change while doing this?

[AudiBMWSX45]

A few questions:

My mechanic told me that my "drive belt / AC belt" need(s) to be changed. He mentioned that these are "packaged together."

I'm not sure what he meant - is the drive belt / AC (air conditioning/accessory?) the same part? I think it is, but I'd just like to confirm...

Also, is this the belt that Bav Auto refers to as: Belt - Serpentine - Water Pump - Alternator - 7k x 1635 Part # : 11 28 1 432 724.

While doing this, what else should I have done? I think I should have the water pump and thermostat replaced at the same time to save labor - is this true? And am I missing anything?

TIA.