Quality beans must have the right genetics, the right climate, and must be fermented and dried properly immediately after they're picked. You have no control over this process, but you can seek out high-quality ingredients. In my own searches, and in speaking with professional craft chocolate makers, there is really one reliable place to purchase such beans in small quantities: Chocolate Alchemy, which sells about 20 different varieties of high-quality beans from around the world. Don’t buy "raw" cacao beans for chocolate — they typically have not been properly fermented or dried.
For a sweetener, you can use any kind of sugar you want although organic cane sugar is what most artisan makers use. Any kind of sweetener with moisture in it, or a liquid sweetener, should be avoided — it will seize the cacao butter in the chocolate, resulting in a lumpy mess that does not even taste good.