Well, we do the whole Seder in Hebrew, but if there are guests who don't understand, then someone who speaks English will sit next to them and explain. It's a big thing, the Seder night, because it actually tells the story of the formation of the Jewish people, their basic history, and it is a commandment from the Torah to tell that story every year on Passover eve.
As for wearing a cross: Star, if it's not too obtrusive that's OK. Once at a Seder night at my parents' home in England, one of the guests was a mother superior of a convent, and I sat beside her and explained. It was slightly embarrassing at a couple of places, but I sort of ignored them and she also went along with me. I'm not sure whether she realised I was missing out bits or not!
We are orthodox, so there is absolutely no bending of the rules. That means four cups of wine (or grape juice is also allowed), and quite a lot of matza have to be eaten, along with bitter herbs etc. etc. Yes, it is fascinating, full of symbolism, the children all love it and look forward to it every year. There are the four questions to be asked, and usually the youngest child asks them in a singsong that he/she has learned. It is very traditional, full of meaning, and full of fun as well.
Star, you and your DF will always be welcome -- please come! I promise you it will be an experience you will never forget!!!
Love, Esther
Oh yes, by the way, I am named after "that" Esther. And my father's name was Mordechai (Esther's uncle in the story). And I have a son who was born on Purim (which happened to be 29th February that year), and he is a joker and prankster to this day!