As far as I know they don’t particularly love sugar because they are compelled to stop and count every grain of it. I have been sitting on this ask looking through my books and searching my mind for any memory of fairies liking sugar and nothing came. Sorry! Maybe that idea came about because of the Sugar Plum Fairy in the Nutcracker Suite. Sugar plums are a sweet candy, and brownies are known for liking honey and cakes and things.
I think harm from casting spells is extremely rare. And I did banishings when I was young and new and they just worked. I also think you need to ward your home for protection. But ultimately, you just need to have an alarm system and the police need to know he has threatened you.
I like these spells a lot: http://www.sacred-texts.com/neu/celt/cg2/index.htm
Most of these spells do not call for any herbs or ingredients to be ingested or applied. If one does, please look to see if there is another chant for the same malady that doesn’t. Unless its a very simple culinary herb that the patient knows they have no contradictions with, its best for a beginner to avoid working with herbs for healing. There are many wonderful programs to learn about herbs for the beginner I can suggest to you if you are interested.
Also, if you don’t want to use the gods and saints listed in the chants, many pagans have substituted in the pagan figures that were absorbed into saints and angels and god during conversion. St Michael/Arcangel Michael with Lugh, St. Brigit with Brighid, Rapheal with Mananaan McLir and so on. There is a historical relevance to doing this because its a common practice among many folk traditions to change up the names used in their magics to the newer religions based on similar attributes. You find it across the Indo-european traditions and even in Afro-diasporic traditions in the states. As its part of the constant cultural exchange, its reasonable to continue the practice if you wish to do so. If you are more secular based you are welcome to call upon the more elemental powers that are the gods/angels/saints were associated with, Raphael/McLir the sea, Michael/Lugh powerful warrior light and fire, St. Brigit/Brighid spring sunlight, gentle fire and healing water, and so on.