As for unsprung weight…

“A stock 2007 Ford Focus was compared with an identical vehicle modified with 66 lb (30 kg) of ballast fitted to each wheel. The weight was distributed between rotating and nonrotating unsprung masses as to broadly replicate Protean Electric’s PD18 (18-in diameter) wheel-hub-motor unit. The project plan included three phases of analysis and testing.

Phase 1 focused on modeling of different modifications, including suspension spring, bushing, and damper rates, and different tires and pressures, and their effects on the IWM-equipped vehicle. It was determined that simply fitting a standard Focus ST suspension (an upgrade on the stock base car) would be a good practical solution.

In phase 2, the stock vehicle was modified with the Focus ST suspension. This setup included revisions to the front and rear spring rates, dampers, and the rear antiroll bar. In phase 3, the Focus with the modified ST suspension was retested. The process included a subjective vehicle assessment, objective ride and handling tests, on-road shake measurements, and two-post shaker rig measurements.

The studies concluded, and the presenters argue, that while the vehicle carrying the greater unsprung mass at each wheel did display perceptible differences compared with the stock vehicle, those differences were minor and can be mitigated using “normal engineering processes within a product development cycle.”

By fitting the upgraded ST-level suspension to the car replicating one equipped with Protean PD18 in-wheel motors, the vehicle’s handling and on-center tracking were improved back to reference. Overall, the effort conducted by Protean Electric, Lotus Engineering, and Dunamos may help convince skeptics that the addition of 30 kg of unsprung mass per corner will not adversely impact overall vehicle dynamics and can be addressed fairly easily with cost-effective countermeasures.”

http://ev.sae.org/article/9493/

Yes, the motors will be subjected to more water, etc. We build electric trolling motors that spend their working hours under water. And bow thrusters for large ships that spend their lifetime under saltwater.

“Each Axial Flux 3 phase AC Induction wheel motor has a nominal output of
75 kw and 625 Nm of torque with a peak output of 150 kw and 1,250 Nm
giving the vehicle a total peak output of 600 kw (800 hp) and 5,000 Nm.*”

http://www.electric-vehiclenews.com/2013/03/wheel-motor-validation-testing-confirms.html

He probably has ties to Evans electric. Because there are hardly an news about it elsewhere and he disabled comments when I asked about it. (And revoked my commenting permissions like a real jerk…)