I stayed in Cancun and it was a day trip for us (our tour took us to a cenote, Chichen Itza, and a neighboring town Valladolid. We only stayed at the pyramid for maybe 2 hours but It was raining when we arrived. There were tons of street vendors (expensive! do not buy from them and they are aggressively trying to sell you stuff beware!) I say hire a guide so they can tell you the history and walk you around the grounds so you know what you are looking at - you won't spend as much time as you think there - as the other person said half a day max a few hours in the morning before the crowds would be best.

There is a big collection of buses and cars nearby, but not sure where they go. Sorry

This is just an idea.. It's what I did in January 2022. I took a tour from Cancun to Chichen Itza. Then, instead of returning to Cancun, I stayed at Mayalands. You can take a taxi to Piste from Mayalands. The down side is the taxi from Piste to Cancun is probably 200-300 dollars. I didn't want to pay that so I took a bus from near Piste to Cancun. It was cheap, but the bus station was a bit rough and not sure I'd do it if I didn't understand Spanish. All depends upon how much the rental car is. Be careful of highway scams. I think there are tolls, too.

They only allow 3000 people on the site at any one time so I would advise getting there early. Some of the structures you can touch but most are protected now, due to people putting graffiti on some of the stones.

I answered in Spanish, but here's my answer in English. Wherever you stay, there's a tour company that will pick you up if you're happy paying for it. I was in Merida, and they also have public buses that run to Merida. You can also take a taxi. Chichen Itza is closer to Merida than it is to Cancun. I had my own rental car, and the drive was easy and safe on good roads. However you decide to get there it is worth the effort. At the front gate they have tour guides that speak various languages. I suggest that you spend a few dollars on one. It helps the experience.

We were there last week and that entrance was not open. I do not know about the night show. Many of he light posts had been removed though.

No stairs, but very busy and a lot of walking. Ek Balam is the only Mayan ruin in the area that can be climbed on.

No tengo el dato sobre si las personas descapacitadas pagan o no. Lo lamento.

PS - Even if you don't pay for a tour, it's so easy to stand near someone giving a tour to hear in on things if you'd like. I wouldn't make it obvious unless you plan on tipping or something, but if you're just taking photos and listening in, looking around :)