Either bring the wheelchair with you or rent one and have it delievered to your resort. It'll be cheaper than renting each day in the parks, if you hop to another park you don't repay, but they may be all rented for the day, you'll have it at your resort, at DTD, etc.
My dad was wheelchair bound. We took him to the airport in his manual chair, he boarded the plane, etc using that. We had a power chair waiting for us in our room when we arrived. Carried a cord around so we could recharge in restaurnts during the day. I think its $150 for the week or so, it was several years ago, but soooo worth it to have it right there.
In the parks my dad couldn't transfer to rides, so they'd let the rest of us go to the handicap entrance anyway so he wouldn't have to wait as long, or do a ride swap thing where some of us would be in line, others would be with him and we'd switch. It would depend on the ride and the line lenghts. Sometimes they'd take him into the control room so he could see things behind the scenes while we rode. He liked that more than when he could still ride the rides, lol. There's ramps everywhere, even at mini golf, so he could go everywhere. We did have an issue one night leaving TTC trying to get to our resort. Tons of buses came by full and the bus drivers didn't make guests get up from the handicap section for his wheelchair to fit, or the bus didn't have a lift (I think they all do now). His battery pack was dying and he was in pain so after the 5th bus or so I got in the stairwell and wouldn't get off until the bus driver did something. He called in for help for us after some of the guests on the bus started grumbling that I wouldn't move. Within in 5 minutes a bus showed up with VIP Only (our last name). They let only us on the bus and left everyone else at the TTC waiting since they could squeeze onto the next bus. They took us right to our hotel and gave us a phone number to call the rest of the week should we ever have a problem again. We didn't, but it was nice to have just in case.
The handicap seating for parades was great, the characters often stop by, the Queen of Hearts gave my dad a quick kiss on the cheek, it was hysterical. CM's really go out of the way to help, but don't expect automatic front of the line access either, it's not a 'meal ticket'. When he rode It's a small world with us, we went to the handicap entrance but waited the full 15 minutes everyone else waited, and then got on the next accessible boat that showed up.
As to decorations, they'll be up.
