Omgosh yes! Ms. Queen has LOTS of experience with casts, albeight it was when she was little as she was in serial casts since 4 days (she had both her feet all the way up to thighs and any given time) old up until she was about a year and then periodically again after each surgery over the years. Confuzzled gave some good ideas.
Some schools have weird rules about the backpacks and won't allow them to have them through the day with them. This is a mandatory request that they can NOT deny her to carry her things. Wheel chair she can hook it on and then if she goes to crutches have them go to having a "helper" carry things because there is no way she can maneuver with a backpack too at that point in time. You must do this ahead of time and not wait.
Having a roll in shower will be good IF the wheelchair can get wet! Some the seats can't but ask the orthopedic doctor for a script for a shower chair. That will be more helpful actually to her. Do you have a shower head with a detachable hose? If not, invest in a very cheap attachment (they go on faucet head or shower head depending on what you choose) as that will also make life a heck of a lot easier and, if is embarrassed to have someone with her, will make her feel more independent and comfortable being able to shower alone safely to a degree.
Garbage bags can work but I'm not so sure that a head band may be tight enough to keep water out. If you get ANY water inside that cast, you are going to have a mess of macerated skin (broken down) and ick! You do NOT want to have to go through that! Trust me. What you can do is use the bags but use duck tape just above the line you put the head band so that area is nice and tight around the leg and THEN put the head band at the top. This way it's tight around leg so not to get the water in and then the head band allows for comfort on the leg itself (the part that actually touches).
Itching, ah, now this is where she's going to get miserable! Do not ever put anything down into the cast. You will hear this over and over and over but you would be amazed at how often people do it, especially kids and then there is big problems! They use rulers, pens, pencils, back scratchers, opened coat hangers, etc. Then you risk scratching or cutting the skin and getting an infection (REALLY BIG problems them!) or those items get stuck/lost in there. At first there is going to be the swelling so itching probably won't happen until after it goes down (that's why they most likely will have her have it elevated to keep swelling down and believe me, it WILL help with pain. Let it not be elevated and see how much worse the pain gets!). Here are what you can do: give benedryl (make sure it's ok with your dr first please), use a hair dryer on COOL setting to blow air into the cast on either end (it' a little more tricky with a bend in the knee if she has one- we've had both kinds), use TALCUM or CORN STARCH powders to get down into the cast to soak up the sweat that is causing the itching. Do NOT use baby powder or anything like that! The other 2 suggested wicks up moisture and are meant to do the job safely and with out stink. A better idea when using the powder, if you can, is go it outside or in an area where you can also use the hair dryer on cool/low setting to blow the powder into the cast so it gets down in and evenly distributed. If you just pour it in it tends to get down in there but in BIG clumps in a single area then nicely dispersed. It's a little more tricky when you are trying to put it in from the ankle/foot end but it CAN be done with a little patience!
As for transportation, does your difficult child have an IEP? Get a temporary rider in it for her to have special transport (if she is a bus rider) for their lift buses to accomodate her wheelchair when in it and then later same private transport due to long leg casting as she will NOT be able to walk up the stairs on the normal bus, even with help real well since she does not use crutches on a daily bases in her life (aka, not an "experienced user"). Even if they have to provide a private vehicle of sorts, they must do it! This is ONLY if she has an IEP however. If no IEP, you may not get the later part of my suggestion. You SHOULD be able to get the first part though. Also, ask for them to allow her to get benedryl and the powder at school if necessary (do they have a school nurse?). She may need that too.
Finally, I wouldn't suggest she attempted to wear any shoe on that foot for the duration but I would suggest the booty kind of slippers like
these. Her feet may go from hot to cold at times and you also will want to be able to roll up or down to the ankle as swelling goes up or down too. Of course there are many kinds and colors, just make sure that they can open up around the ankle area to allow for swelling.
Oh and for fun...for her and friends...give her a little gift bag with unique markers, all colors, glittery, etc for her classmates to sign. Even stickers if you like. It makes it much more fun and decorative besides just "signing". You could always, as a gag, give her one of those bells you put on bikes or something similar that makes noise so that when she walks through halls or where there are people she can ring it or make the noise to alert people she is coming through. They will turn and look and less risk of getting bumped!
As for post surgery infection casting...been there done that too and yes...we've experienced a very bad one. Enough that difficult child had a picture line for 3 months with antibiotic. Don't worry as it's rare BUT...if you start smelling a really foul smell, GET TO THE DR! That's infection!
If I can think of anything else I'll add to this. If you have any questions that you can think of that I didn't address or that come up, please feel free to ask here or PM. I'm very serious as I am very experienced with this. difficult child was born with severe bilateral club foot and a congential knee dislocation so I'm not kidding about serial casting and our experiences!