Few compressors have the capability to run off 12vdc as well as 110vac because the wiring is different. That is a cool feature. I would be wary of the 12v capability, however. Some cars need the engine running to use the cigarette lighter. Many cars nowadays don't even have a lighter at all and instead have USB power or 110v outlets.

The obvious solution to the problem of not trusting your pump's pressure readout is to buy a separate gauge that reads up to 90psi.

I have no guess about the 10 bar minimum on the compressor.