Filtration plumbing

[Michael M]

hello, i have been thinking lately a little bit about redoing the plumbing in my 75 gallon tank, the current setup is a Fluval 404 canister filter with an anti-siphon inlet (drawing water from the bottom) and regular outlet (outputting at the top) both of these are factory default pieces that come with the filter and have been placed in the center of the tank at the back, inlet on left side of the crossbar and outlet on the right side of the crossbar pointing directly forward, the design i am going for will resemble something like this CustomFlo Water System Complete Kit by Pentair Aquatics of course as with every project you need to start somewhere so i will start with some questions that will give me some better ideas for optimization

1) what is the inner and outer diameter? replacement packaging just says 17mm (11/16th inch), this info i would need in order to start pricing the parts
2) everyone knows that the inlet of a filter goes at the bottom and the outlet of the filter goes at the top, what i am wondering is what is more efficient, to have the inlet and the outlet of the filter located at opposite ends of the aquarium or beside each other?
3) would it be worth my time / money to incorperate multiple inlets and outlets at different heights in the aquarium like the custom flow system has or would it degrade the efficiency of the filtration system?