How difficult is it to regulate the temperature?
It’s not difficult but it’s not an exact science, which is part of the charm to me.
If you are familiar with how a Kamado Grill works, there is usually a fly wheel vent at the top and a large slide opening vent at the bottom, the less air flow you allow the lower the temperature
But a number of factors play into how hot it burns besides the vent openings, type of charcoal you burn, the wind, etc.
If you are going to cook something low and slow the biggest thing to learn is patience don’t try to rush it, brisket is the hardest IMO, you can easily spend 8-10 hours or more cooking a larger on, so plan accordingly.
Search YouTube for some Kamado Cooking videos and watch an experienced griller, that’s what I did and they were very helpful.