Outdoor pre-filter can be installed later but your plumbing work must be getting ready first. You can ask your filter provider on what kind of spec and measurement for the standby paiping. For eg of mine, pls refer to post#395 in this thread.

As for the autogate wiring, yes you got to conceal the amor cable first of all before the tiling job, and also your other wiring if any for the additional lighting in the car porch area. Pls take note to mark the concealed location of your amor cable too if you are going to install a folding gate with track. You sure not want to cut the cable by accident when you are cutting the tiles and flooring for the sliding track. If swing gate, no concern on the marking.