If you use brushes, you'll get enough airflow through the brushes, and the brushes can be pressed against the work surface (which is why brushes are used in the first place.)
Because I didn't have enough of the strip brush I wanted to use, I ended up using door weatherstripping. Only problem it's not the most effective once the base runs off the workpiece, but this could be worked around by placing scraps the same thickness as the workpiece around the area. Also, I first made the hole for the spindle just larger than the diameter of the collet, and when the collet went all the way down, the vacuum created would literally suck the shoe onto the workpiece! enlargening the hole slightly would help, but I think using brushes eventually would be better.
As far as suction, it would be great to have a high powered dust collecton system. If your dust collection system can overcome the pressure of the blowing air of the router exhaust AND still suck out dust then you're fine. If you're like me and don't have the space or juice for a good dust collection system, and havev to use a ShopVac or other, then you'll have to direct the router exhaust away from the shoe area in order to have enough "suction" in the shoe. Also the less powerful your vacuum is, and the smaller the hose, the smaller the volume of space should be within the dust shoe...