Electrical interference questions for speaker cable and adjacent subwoofer power cord


AudiogoN Team,

I am getting a set of speakers with built in powered subwoofers.  If the subwoofer amps are onboard the speakers, I need to run the power cords for the subwoofer amps with a routing that is parallel to and adjacent to the speaker cables for the mains and subwoofer.  (I plan on using a surge protector for all the electronics, so the subwoofer power cords would have a similar routing as the speaker cables from near my receiver to the speakers.)

1) Do I need to worry about electrical interference from the powered subwoofer power cords running to the sub amps in the speakers if the speaker cables are parallel to and in proximity to the power cords?  

2) If interference is an issue, how far apart do they need to be spaced to avoid interference ( a) power cord from speaker cables, b) subwoofer speaker cable from main driver speaker cable)?

3) if interference is an issue, is there a type of speaker cable that I should get that minimizes the interference and enable close placement of the speaker cable to the subwoofer power cord?

4) if interference is an issue and I ran either the power cords or the speaker cables through a metal pipe, would this eliminate the interference and allow the speaker cables and the power cords to be close to each other?  Only one type would be placed in the metal pipe.

5) For these custom built speakers, I may have a choice to have a) the subwoofer amps onboard the speakers or b) a single subwoofer amp not in the speakers that would instead be located by my receiver, which would then have its own speaker cable that would run to the subwoofers onboard the speakers.  Since this may be a scenario, is it better to have the subwoofer amp onboard the speakers or off of the speakers?  

Thanks in advance for your guidance.
michiganbuckeye
No problem with ANY juxtaposition of power cords and speaker wires! Naturally a tidy layout looks better! An amp located near your receiver/preamp/main amp is my preference. That way you can have an active crossover in the same location to split the signal to the subs and main speakers amps.
I had a system set up that way using four mono amps - two for the main speaker pair and two for the bass speakers. And an active crossover to route the signals from the preamp to the respective four amps. 
I have never found any interference from power cords lying near (or on top of) speaker wires! Though the neurotics will be aghast from my statement!