The star is totally an errand! Lucasta would like to offer her a power point to read this set of recipes for medical potions, and brew some to have on hand in case of an emergency. 

Awesome, can do. Are those recipes in the books she has already or does this mean another stop at the library?

They are recipes in books she already has! 

Three of them are specifically designed for compliance with the masquerade while still being useful to mundane humans: one is intended to be huffed by a witch before beginning rescue breathing, at which point the potion is transferred as fumes to the lungs of the patient, where it works to repair and open alveoli. The second results in a powder that looks and tastes like salt, intended to be stirred into chicken soup (or vegetarian equivalent) whereafter it works to heal respiratory symptoms at a plausible rate and specifically prevent worsening of symptoms. The third is brightly colored and slightly artificial tasting and very, very hydrating. 

Cool! She has never made a potion before so she isn't going to make all three at once even though her hydron enables that; she will start with whichever one looks mediumest in complexity and then maybe do the other two simultaneously.

The Magic Gatorade is the easiest, the soup salt is the middlest, and the mouth-to-mouth resuscitator is the most complicated. 

Soup salt first then!

The recipe involves several kinds of actual salt, some seasonings, and the last sip of water in a glass you've drunk the rest of, poured into the cauldron at various points and stirred in specific ways. All told it takes about ten minutes to put it together and then it wants to sit until it dries, which takes about another twenty minutes. 

Huh. While it's drying can she use the hydron features to get started on the next two?

She can definitely do that. 

Ingredients for Magic Gatorade include regular gatorade (or substitute in alternate Sports Drink, which should fit the following parameters unless you care to take a risk) and rehydration powder; the resuscitation vapor's ingredients include "something carbonated," cornstarch, water that has either had bubbles blown through it or been poured in a thin stream from one container to another for a certain length of time, the ashes of an aromatic herb, and someone's breath. 

She does not have a sports drink! She will zip out to the school store to see if they have the ingredients she needs; she actually already had a few spices since not packing clothes and having infinite space in her landscape meant she didn't need to pack light, and sometimes she'll bring home restaurant leftovers and they will include steamed broccoli even though that's the worst thing you could possibly do to broccoli and she puts garlic salt on it. Gatorade, cornstarch, a straw for bubbles, an aromatic herb, she has perfectly good breath, a soda or a sparkling water or something.

There is not exactly a school store as such but the town area has lots of stores, some of which will a) take cash, and b) mention this online. 

Well, anything sufficiently like a Couche-Tard will do the trick.

There are relatively few of those, but one relatively nearby. 

(When she gets there, she may intuit that it was put together and run more by an enthusiastic muggleboo than by anyone who actually had experience of mundane convenience stores, but she can acquire her potion ingredients just fine).

...what are their weird selection options? She does also need containers to store her potions in.

In terms of containers they have less in the way of plastic gladware and more in the way of ornate glass bottles and decorated metal boxes and a slightly perplexing amount of cling wrap. 

Well, she likes orante glass bottles and decorated metal boxes, especially if she can charge off them but probably these were churned out in large batches.

They were churned out in large batches but even a factory glassblower takes some pride in their work. 

She takes the pridefulest handful, and the ingredients, and a couple kitchen timers to track her potioning, and pays out of her spending money and flies back home to make the potions!

And when her potions are brewed, she gets a point of Favor from Lucasta, which can be exchanged for a power point at any time. 

Yaaaaay. She thinks she will hold onto it for the time being, learn more about all the things she has options for, maybe save up for a large purchase if she doesn't pop out of her digicasting class going "omg I need a rank in that right now".

She reads more of her potions book, armed with recent practical experience.

The book is more of a recipe book than a theory book but there are a lot of recipes in it, ranging from cures for obscure medical ailments to flavorings that work better than normal flavorings--completely overwriting the underlying flavor instead of adding to it--to a minor working memory enhancer. 

Ooh, a working memory enhancer!! Do the flavor ones do the meat flavor for tofu thing she was wondering about?

There's one that does, but requires a scrap of the meat in question as an ingredient; the rest are all flavor-specific and not for that flavor specifically. 

Well, you could get the ultra humane stuff and chop it up real small to spread it around on lots of foods but it is presumably not kosher if you do it that way.

What would she need for the memory one?

The memory potion wants several sprigs of fresh rosemary, a fish bone, a small drawing of an elephant (it can be done on anything, but the potion will take a lot longer to brew if it's on something like stone or metal instead of something that will dissolve without too much fuss like paper) three different colors of dyed sugar, and water. Tap water is fine, river water is fine, salt water works but then you have to add these three extra steps to compensate for the salt. Also you're supposed to say something that you have at some point forgotten and then remembered again while you stir it.