RUT955's antennas are omnidirectional. Therefore you could place antennas in any desired position (on the car's roof, building walls, etc).
Take note that for best effect, router's antennas should be spread as far apart as possible. Of course, you can place antennas close together - they would not interface with each other.
RUT955's antennas were designed to be used indoors. Of course, you can use antennas outdoors too (they will be working without any issue), but take note that antennas might loose their marketing appearance from direct sunlight and rain. Just make sure that water from rain would not be able to flow to the router through antenna's cable.