Looking at these posts, my questions are way more basic, but I still would appreciate any input. Got some warranty work done at my dealership (new steering wheel as the paint was peeling/chipping). It's almost 4-years old and nearing 40k with lot of stop and go city driving. Dealership tells me the rear pads are 3/32 and 4/32 and need replacement. They quote me $429 for pads/installation only. Another dealer quotes me $600 for rear pads and rotors claiming the G35X rear rotors are too thin to be machined and recommend replacement with the pads. They also quote me $119 for brake flush, but think I should wait for 60k.

Spoke with an independent shop that has a certified Nissan/Infiniti mechanic and they use OEM parts. They quote me $197 pads/installation, tell me the rear rotors can be machined, and if needed it's $20, and $89 for a brake fluid flush. I thought generally brake fluid should be flushed with pad changes, but maybe I'm wrong. Obviously going to this indy for the rear pads, but my questions, not knowing much at all about brakes and looking for advice so I understand the situation even though I trust the indy:

1. What determines if rotors should be replaced or machined with brake pad changes and is it typical to either machine or replace rear rotors with pads on an '08 G35X sedan?;
2. Is a brake fluid flush appropriate at this point? Never changed the brake fluid before;
3. Is it typical for only the rear pads to first need replacing? The dealer did not give me the measurements on the front pads, but I suppose I can get them.

Thanks for any info.