You can charge to your room if staying at the Swan/Dolphin. I don't think you need reservations there if you go early.
When staying at the Swan, I ordered sushi for carry out to our room 4 times (my kids love sushi, but I must explain DH is Korean, so we eat rice and such a lot, and DS was born in Hawaii, lucky guy, as we were there for a few years).
I eat sushi weekly (if lucky) and Kimonos food is very very good. You pay for it though, as food for me and two kids, ages 9 and 7 at the time was usually about $80 or a bit less. Okay, maybe we ordered a lot (and ate it!)
Kids can order rice, miso soup (they charge more than most restaurants for this), maybe a shrimp tempura appetizer. No set kids' menu - DS loves tuna sushi and DD likes the tamago, california roll, maybe some soup. I love it all, and it was fresh. Didn't like the rainbow roll though.
I carried out last time I was at the Dolphin with my friend and her 4 kids (we left our DH's at home, and they put us close together) and I ran into her at Kimono's. She said that they agreed to bring kids' meals from Gulliver's for her 4 kids so she could relax and order sushi there - you could definitely ask when you get to Kimono's regarding that. The kids menus from Gulliver's were about $5 or so, chicken tenders, etc...
Kimono's is very quiet when they first open up in the evening - I think they get more crowded later. If you have kids I'd do the early evening, and ask about the other menu.
Overall, I found the service at the Swan and Dolphin very much above average (and I'm a hotel snob, sorry, but I am! I love our local Ritz Carlton and they know us well

)
I do highly recommend the place as it's a nice break from Disney. I will miss it on our next trip.