Track lighting newbie question

My garage has track lighting from previous owner. I want to change the lamp units to a different style, but I can't figure out how to remove them from the rail? Is it suppose to slide too, because it doesn't seem to slide.. is it just rusty?

Another question, I want to add a 2nd track myself. The existing one uses a 2 prong plug. When I buy the track from stores, does it come with bare wires or a plug? How can I convert it to a plug?

 

Usually you press a lever or turn a collar, and then twist the fixture a quarter turn to remove it.

Some come with cord and plug attached; with some you have to buy a "starter" fitting and add the cord yourself. Prefab garbage disposal cords work nicely for this, and if you need a cord any longer than that you should go to some sort of permanant wiring method rather than use a long cord.

Regarding the two prong cord end on the other one - this is not preferred. If at all possible, I'd change that cord to a three wire cord with a three prong cord end and the ground wire properly grounded to the track.

It's safer that way.