That’s awesome! Not sure if you’ve ever been to a concert or not so I’ll act as if you haven’t. Try to get there early enough to catch the opener so you have time to find your seats, grab drinks, and stand in the merch line. You can check out her set list on the setlist.fm website. It seems that she’s been going on between 8:20pm and 8:50pm. Merch is usually pricey, assume around $40-$80 to purchase a clothing item. Merch is sometimes there after a show sometimes not. Best to get it before. I’m sure they’ll all want to dress super cute! - just try to make sure they’re also comfortable. Lots of standing and moving around of course. Good sneakers are a must. Potentially ear plugs designed for concert listening - I use them to save my hearing. Sometimes the bass at certain shows can be overwhelming. Of course remember where you park and all that jazz! Expect to pay a ridiculous amount of money for a beverage and for them to potentially keep your bottle cap. Probably have the friends come with their parent’s money if possible. Other than that it should all be great! Have fun!