hey doggy..
the collars are just the same.. you just type in the freq ie; 433.333 and save a dogs name to that.. so yes you can nominate what collars.
yes the antenna fold back into the body of the receiver.
mate tracker with there new ones coming out soon have the plug as well.. so not knocking tracker, but i think everyone wants to be the top dog of telemetry.. and so new features are added to give that extra marketing ability.
433mhz is legal. apparently the radio signal is not as large as the 151/2 so comparing them both you would need at larger yagi to get more valuable readings from the 151/2 then the 433.. so i have been told..
hence, if required for LONG distance, you would only need a smaller yagi on this new setup than from the other brands on 151/2 that are out there now..
its going to be the future.. when i find out more information i will let you know.. but form what ive seen, with the digital reading for accuracy.. nothing will come close to it.. even complete telemetry novices can not fail.. no possible chance of running in the wrong direction as a lot of people have found.
cheers