An ixp is a switching fabric not a building(NAP).

At the same building where you connected with Vodafone in the past, you connect to interlink instead.

Instead of one to many you connect one to one.

Just to clarify one thing, the fact that's you're connected to an ixp doesn't automatically mean you have to accept any routes or traffic over it. And yes some of them allow you to sell/buy transit over the IXP fabric so instead of buying one connection for transit and another for settlement free pairing over the IXP, you do all that over one physical connection