1) You will need a silicone heart mold to make these truffles (unless you are adept at spinning hearts out of air in which case I am very jealous). I bought mine many years ago at IKEA (sold as an ice cube tray). You can find these molds easily online - Amazon has many to choose from.
2) In their pure form, cacao and cocoa powder are used interchangeably to refer to the basic powder made from whole, roasted cacao beans that have been ground up. The powder itself contains very little fat and no added sugar. This is not to be confused with the more common commercial cocoa powder used to make hot chocolate which is processed and sweetened. You can find natural cacao and cocoa powder at health food stores and many large grocery stores.
3) If you are new to coconut butter, it is the pureed pulp/meat of the coconut - unlike coconut oil (which is extracted and separated from the pulp of the coconut), the butter retains its native fiber content.
4) Coconut butter, like all saturated fats, is generally solid at room temperature. Coconut butter is a little trickier than coconut oil to melt. The butter's texture varies considerably and it also burns easily. I do not recommend melting coconut butter in the microwave. The water bath method (double-boiler) is a gentler method (a warm but not hot oven might also do the trick). If you wish to keep these truffles 'raw' you can simply heat the coconut oil over a bowl of hot water (using the double-boiler method) and gently coax it along until it melts -- as opposed to heating more rigorously (and at a higher temperature) on the stove top.
5) I prefer chocolate (and desserts generally) on the mildly sweet side - the vanilla and mint add wonderful taste but you can also modify the maple syrup quantity to suit your taste.