Congrats on the MiTo.
The biggest problem you are going to have with it being black is the dreaded SWIRLS. You also mention that you work in an area which deposits large amounts of dust onto the bodywork.
Thus, at this stage of your car's life, the most important thing you have to sort out is your washing regime, not what kind of wax you apply.
The biggest cause of swirls and therefore unhappiness by countless owners of black cars is swirls induced while washing and drying their cars. These are caused by countless specks of abrasive dust being wiped into the surface while washing and drying.
A few tips:
1. Don't blast your paintwork with a high pressure hose. It serves no purpose and will do more harm than good. Rather give it a light rinse to soften the dirt and wash some of it off.
2. Use a good quality car shampoo (not dishwashing liquid)
3. Do not use a sponge or chamois (especially the latter!!) Buy a microfibre or lambswool wash mitt.
4. Use the two bucket method - one bucket for the soapy wash solution and another to rinse off your mitt between applications.
5. Dry your car using a microfibre towel - again do NOT use a chamois.
6. Wash your car often - Like every week!!
7. Apply a good quality Carnauba Wax four times a year. I cannot comment about the kit you were given with the car but if it was provided by the stealers then its probably cr*p.
Lastly, having bought a brand new car (YOU LUCKY CHAP) you have a clean palette (canvass?), so to speak, so you have the perfect opportunity to start off with a pristine car and keep it that way.