Does it regulate?
Well, they can, but it depends on your application and you probably don't want to.
Transistors in digital or logic mode are driven fully on or are fully off. In an ideal world they would not get hot, because when off their power output (as heat) is V times 0. When on, an ideal transistor would have a power output (as heat) of I times 0.
In reality, a fully off transistor does indeed dissipate zero watts.
But when on the Saturation Voltage dropped Collector to Emitter (Vce) is 0.2V or so. So the power dissipated is I times 0.2. That is
what the voltage Vce matters, especially for high power transistors (though it does not vary all that much). (By the way, in this case,
I is limited by the load or supply, not the transistor, so too big a motor lets too much current through and the transistor blows.)
You can also run a transistor in a mode where is is only partly on. In that case the power output is calculated in the same way.
And will be bigger, which is fine with a big enough transistor. Which is why you have to know the ratings of it. Also controlling it
exactly in such a mode is harder.
The specs refer to maximum voltages and current in specified conditions. For example, Vcbo is voltage allowed between collector and base before the semiconductor breaks down permanently. You should choose a transistor where these ratings will not be exceeded under any condition of your circuit. Vebo is probably the biggest reverse voltage you should put between emitter and base - in your circuit that is going to be zero. Vceo is important in that is the most the transistor will stand before it breaks down - in your case the 7V supply should be no problem. The current specs are the ones to watch more. Dissipation is the amount of heat the transistor can throw away, again under certain conditions, and changes if it is one that you can heatsink - it will be Vce times Ic (Collector Current).
I hope this helps, a bit.