a 7812 regulator will be stable and the best I think. A TO-92 package can handle that amount of current and they are less than a buck probably.
As far as a transistor driver. Of course a npn or pnp transistor will work for you. But I personally like to use the darlington transistor. They wire the same as a standard lets say PNP or NPN transistor, but you get the added bonus that they will turn on with a fraction of the current needed as compared to a standard PNP or NPN transistor. We are talking about nano amps here.