Can anybody explain in user terms what this can do?
The new version has marvel characters and Disney which seems perfect for my 3.5 year old after our trip to disney.

Also is Marvel now owned by Disney?

Our son was delighted when he met the REAL Spiderman at Disneyland last week.

You buy the game and it comes with characters and a gem to place on an interactive mat.
The gem unlocks the story e.g Marvel, Incredibles, Cars etc and the character figures unlock the characters to play as in that game.
You can’t mix and match characters to play in that story i.e Lightning McQueen can’t be played within the Incredibles gem story mode.
There is a “Toy Box” mode whereby you can be any character and create a world for them to play in – this is where you can mix and match characters etc.
Basically, you spend £40 on the game and then £10 a pop to play as the characters. Big money spinner but it’s for the kids so what can you do?

Does it need a console?

Yes.

OK, second question; What type of console?

https://en.wikipedia.org/wiki/Disney_Infinity

The game was released for Xbox 360, PlayStation 3, Wii, Wii U, and Nintendo 3DS in August 2013. A PC version of Toy Box was also released on November 14, 2013. The second edition, Disney Infinity: Marvel Super Heroes, has been announced for September 23, 2014.

Oh, and,

Also is Marvel now owned by Disney?

Yes.