A wheel being out of true would not be that big a problem--there is fairly small contact area and the bearings would barely be able to detect what would amount to a minute angular change. This is actually an advantage of a rim-born wheel vs a hub-born wheel. Anyone who has run a curved piece of wood parallel to the fence on a table saw understands this principle. As far brakes go--if there is a drive hidden in the rear enclosure why couldn't there be a brake hidden in the front enclosure? The handle bars are splayed, and forward pressure could activate a front brake. There could also be coaster brakes on the rear wheel. Gearing however would require more bulk than is shown in the photos.

They've built spokeless, hubless wheels before--and yes, they are not practical--especially in an urban environment with potholes. The stresses on the bearing surfaces are too great. The cantilevered seat post has been used very successfully in Zipp and Softride frames. the V-joint at the bottom bracket looks way too weak, but could be made to work with a carbon gusset or open brace closing the triangle.