An interesting implementation.

The "blue flat things" are a pair of Y caps, they appear to be in parallel, connecting the two USB grounds [EDIT: or at least shields] together. Unfortunately they will also couple high frequency ground noise.
Yes, the black box is an isolated DC-DC converter. Unfortunately, if you bypass it and use the DC jack (9-30V) it will still be using the on-board SMPS (U4) to power the isolates side. Noise level will depend on quality of design.
The 480Mbps claim is suspect. It looks as if they are using an ADUM4160 with the number ground off. If so, it is capable of USB2 Full speed (as they say in the description) but that is 12Mbps. It's USB2
High Speed is 480Mbps. I am not aware of any single chip USB High speed solutions at the moment.