Hi LD, I don't know what top this is but I'd say the necklace and scarf probably don't come with the top. Read the description and it should tell you, if it does. What size do you normally order in her things? for some of her things I can size down to a Small, some of her tops run large.
But in a top that's supposed to be blousy and relaxed, I'd think you'd either want to go with your regular HSN size or size down one.
Just from what you've said about the top, I'd size down one size if that is an option and they have a good range of sizes. Then again since it's so low priced you could order 2 sizes and just return the one that doesn't fit, if you know the top won't be back and you really want it and don't want to chance getting the wrong size. Good luck!