Will this caliper fit in a standard toolbox?

At 6", it's compact enough for most drawer setups and tool bags. Stainless steel won't rust if it gets damp, so storage in a garage or truck bed won't damage it.

How accurate are dial calipers compared to digital ones?

Dial calipers are plenty accurate for automotive work—engine bore checks, suspension measurements, brake rotor thickness. The lock feature here actually gives you an advantage: you can measure, lock the reading, then walk over to compare parts side-by-side without resetting.

What if the dial gets bumped and stops reading true?

The shockproof design handles normal shop abuse, but if you drop it or clamp it in a vise, the dial can lose calibration. Recalibrate by closing the jaws completely and ensuring the needle returns to zero before your next measurement.