Beginner electronics hobbyist needing my schematic looked over
Your schematic doesnt look very energy efficient .Consider the ratio of mosfet heat to Vap heat.In fact your mosfet could Vap.Because the Vap is an element it will have some thermal mass so you could feed it PWM where the mosfet is either on or off .Your expected efficiency at low frequencies could easily be 90%  justification of this figure is with 10milliohm Nchan mosfet which is not expensive these days.You can make pwm with most micros or you could use a LM393 .In fact making PWM is easier than getting rid of the heat.A bonus of this is that your power requirements will be significantly lower.