I googled Edinburgh underground walking tour. It was the first one which came up and it was through Viator. Hope this helps.

Across the street from Scotland Bank, there's a blue kiosk for bus tours. This is not a bus tour, but that's where we met.

Yes, great for all ages.

There isn’t actually anyone hiding who jumps out at you but the guide we had engages in a little fun where he turns out the light and then chooses someone to stand directly in front of when he turns the like back on - stuff like that !

You meet on the Royal Mile, directly opposite Deacon Brodie's pub. There is a tourist booth there.

Hola, no y no es el tour the mary king close

When you go to purchase tickets and pick a date it will show you the times they have available. But I remember they basically had a tour about every hour starting around 10am and even haunted night tours after dark. However since it is underground it not one of the tours that you have to wait till dark to do!

We booked well in advance and people trying to book on the day were turned down

No estamos hablando del mismo Tour, en Mary King’s Close por supuesto y además merece mucho la pena; pero el tour que yo he comentado es uno que intenta hacerse pasar por este y nada que ver, es bastante engañoso

The step is quite high, no handrail but the guides and fellow tourists are very helpfully provided you are not too precious about covid rules and accepting a helping hand.