Planning for a projector

[Eidolon]

Due to my home suffering considerable damage, I'm forced to have to take a considerable rebuild of parts of it this year. This will in part involved work on my 'cinema room', and will require the digging out of the floor to an estimated 1.5 meters, ultimately to be replaced with new dry materials and bought up to current UK regulations when it is redone.
So I have a rather large hole imminent, and am planning on running a number of electric cables through it while I have the chance, getting them out of the walls where they currently are.

I have no idea if I'll ever get a projector, but I'd rather plan ahead while I have the chance. Should I get one, I'll have it wall mounted, high up on the wall behind the sofa, and the cabled for it will run through the wall into an under-stairs cupboard/closet behind. From there, I should be able to run cables to the surround sound and players through a conduit through the concrete to the opposite side of the room, and to the aforementioned machines.

However, having never owned a projector before, and not having actually looked into them once, I'm not really sure how best to go about this.

As my Surround Sound is a pass-through, I would assume that all I need to put through the conduit from a projector is a HDMI cable. Is this correct, or would I need to do something else?
Trying to switch between various players might be awkward as well, I've not looked into that as of yet, not into a screen.

Thanks for any advice available