1) It does require a "system", basically any fantasy TTRPG (e.g., a "D&D" or its many descendants). I recommend Cairn, which you can find for free online.
2) So "Xd6" means roll a number 6-sided die equal to the X and add them. Gold is for gold pieces, the currency/treasure the characters are trying to acquire. Spells here would just be either spells chosen at random or the referee might select specific ones. The "system" you are using tends to provide what spells are available.
No need to apologize! The zine is pretty jam-packed, so does make some assumptions about baseline familiarity with classic, fantasy TTRPGs!