Altium: reuse schematic AND pcb layout

For a very large number of copies use hierarchical design techniques to create rooms repeating circuit blocks a large number of times. After aranging rooms, then you can use Design >> Rooms >> Copy Room Formats to make them all the same very rapidly. This copies everything about the previous template room including component orientations, tracks, vias, text, etc.

You do can multi-channel in Altium, using the sheet symbol.

You create a schematic with ports representing the inputs and outputs to your repeating circuit, then place those on your main sheet, connecting up your ports. When you create your PCB, those circuits will be placed in 'rooms', which you can then setup a single room, then copy it to the other rooms. This will copy alignment, traces, layers, etc, between all the rooms so all are wired up nearly identically.

See http://techdocs.altium.com/display/ADOH/Creating+a+Multi-channel+Design for a description straight from the source.