Considering hiking White Mountain this Sat for a Mt Whitney warm up hike. Will hike Whitney on Mon. I'm going up this Friday 7/8

Does Grandview campground fill up on the Weekends?
Is there bear activity in the White Mountains? Bear boxes at Grandview?? Can coolers and or food be left in my truck at the trailhead?? I've heard the marmots at the trail head can chew the wiring and hoses on your car. Is this true or is it urban legend? How is the road to the trail head? I have a 4x4.
Thanks in advance for any info.