I'm very sorry you and your little one are going through this, OP.
I don't have experience of that specific type of cancer, but my son was diagnosed with a medullablastoma last year and has had 2 rounds of intensive chemo, 6 weeks of radiotherapy and will need another year of chemo. My main advice would be to listen/talk to other parents about their own experiences, if you can; and to research absolutely everything and don't be afraid to ask questions (even when the Drs look at you like you're crazy or wasting their time for asking).
For the first round, my son had 5 days of intensive chemo (2 different types of chemo each day, adminstered via a hickman line. The first ran for an hour; the second ran for 5 hours). He wasn't confined to bed during the chemo, he could move around, play, eat and drink etc., as long as we were careful with the drip stand. Some hospitals will have play specialists, who will visit your child or see them in the playroom (if you wish) and either play with them directly, or provide you with toys/games/activities that you can borrow for the duration of your child's stay.
As he was still on steroids (to alleviate swelling) at the time of his first round, it actually went very well, as far as these things go. He wasn't nauseous, ate like a horse and had zero side effects. The absolute worst thing was the injection he needed 24 hours after the final day of chemo, to help encourage the growth of white cells. It does into the muscle and he found it unbearably painful and it did result in on-going bone pain.
I was told by Drs that the first round of chemo is always done on an in-patient basis, as they like to keep a close eye on the child, to make sure they don't have a bad reaction to the chemo.
All in-patients at the hospital we were at (GOSH) have private rooms, to reduce the risk of infection. Both parents could stay during the day, and have other visitors, but only one person could stay with the child at night. Patients have 3 x free meals a day, parents staying overnight with patients do not (unlike at out local hospital). However, some hospitals will give in-patients familes vouchers to spend on the in-house canteen (about £7 a day), but you have to specifically ask. No one volunteered this information to us - like most things, we only found out about it by talking with other parents.
He had about a week's break after the first round, then had a second round of intensive chemo. However, as he had suffered no ill effects during the first round, at our request, he was allowed to be treated as a day patient. This was much better for us, as it meant he had a proper meal at dinner time (let's face it, hospital food is dire), could sleep in his own bed, play with his own toys etc.
Unfortunately, he was off steroids by the second round, so did feel very ill this time and although still eating and drinking real food (as opposed to liquid feed fed through a tube), was nauseous / vomiting throughout that entire period. Again, the injection after chemo was shockingly painful and the nurse stabbed him three times before she finally got the needle in, so he had blood pouring down his leg by the time she'd managed it.
He didn't need a platelet transfusion or blood transfusion after the first round, but needed both after the second round. Both of these sapped his energy and made him very ill (the exact opposite of what the Drs told us would happen).
With your little one's age, any scans will be done under GA. They can try different types of anaesthetic drugs / combinations, which is important to know if your little one starts having a very bad wakeup experience. For example, my son was fine the first half a dozen times, then each time he woke up, he was absolutely furious and physically aggressive (punching and kicking the sides of the bed or anyone who went near him, screaming in rage, trying to leap from the bed). The time he took to calm down was taking longer and longer and I spoke to at least a dozen Drs/anaesthatists about it until one finally said, 'you know there are different types of drugs we can try?' So they changed whatever they were giving him and, as if by magic, he was awake and coherant quickly after each GA (and he's just finished 30 of them over the last 6 weeks), not confused about where he was, not angry or aggressive.
It is very scary, because everything is unknown. At every stage, I have been terrified, yet we have got through this far. It sounds obvious, but you are the mother; you really do know best. There will be times where you have to fight for your child and you will be "that parent". Steel yourself for it. You can do it.
Drop the arsehole 'friends' who tell you rubbish things like "be strong" (as if you aren't fucking tough as nails already) and keep those who simply listen without judgement or do thoughtful things unasked, like buy you a Deliveroo voucher or offer to come and collect your laundry and do a load for you while you're at the hospital.
Sending you lots of love, OP. XXX