There is signage at the intersections with Bethune and Dunbar. I believe the service roads extend north beyond 117th Ave because of the fact that they display white "speed limit X" signs as opposed to yellow "ramp X mph" signs. 

Regarding the hov designation on the Thru Lanes, my understanding is that there's no High Occupancy Vehicle restriction, you just can't drive a truck and you have to have a toll tag (Sunpass) as opposed to toll by plate.