#1
So I've been looking into putting a bridge humbucker into my strat, pretty common thing I assume. I came across this article from seymour duncan http://www.seymourduncan.com/blog/the-tone-garage/the-philosophy-of-the-fat-strat-single-coils-and-humbuckers-at-peace

The author's main point was, "You can have good notch position tone, or you can have matching output levels. You can’t have both. Choose one and live with it." Notch position being position 2, the bridge and middle single coils together.

The reason for this being that since humbuckers have much higher outputs than single coils, you can either 1) get a humbucker with double the output of your single coil pickups, resulting in matching outputs between one coil of the humbucker and the middle pickup. This keeps a proper tone in the second position, but your output would be much lower in positions 3-5. or 2) get a medium-low output humbucker to match the outputs of the single coils, but then your tone in position 2 would be ruined since one coil of the humbucker is going to be half the output of the middle pick up.

I came across this pickup, http://www.seymourduncan.com/pickup/59custom-hybrid-trembucker
           
           The idea is that, "When split, you get the 7k coil for a much more usable single coil sound."  On its store page it says it has 4 conductor lead wire for multiple wiring options. 

This seems like a great solution to the problem described in the first article I linked. My question is, how would I wire this to keep both coils on in position 1 and have it split so that one coil is on and the middle pick up is on in position 2.
#2
Have a look at the SD P-Rail. With that trembucker I would I would be asking which coil is 7k, the screw coil or the slug coil. I personally wouldn't want it if it is the slug coil.

This should answer your wiring question:

http://www.stewmac.com/How-To/Online_Resources/Learn_About_Guitar_Pickups_and_Electronics_and_Wiring/E-Model_Megaswitch_Instructions.html
#3
I'm the other way around, I don't think the P-rails single sounds very good (or at least not much like a standard strat pickup), and it's very very hot anyway - I'm fairly certain that even the neck version single coil is going to be louder than the 7K coil on the custom hybrid. Unfortunately it looks like Duncan doesn't publish output numbers for the P-rails. 

Auto-split wiring is nice and easy:
https://www.premierguitar.com/articles/Stratocaster_Auto_Split_Mod
#5
There are other solutions.

More pickup makers are makeong a few humbuckers that are actually a pair of their singlecoils in a humbucker housing. This means that the HB operating normally will be identical or very close in output to the singlecoils (of the same type) and when split, will be identical output.

Rio Grande is one such maker. Their Tallboy HB is a pair of their Tallboy singlecoils housed as a humbucker; the Dirty Harry and Dirty Harry Jr. HBs are pairs of their Dirty Harry and Dirty Harry Jr. singlecoil-sized P90s in HB housings.

https://www.riograndepickups.com
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#6
The Hybrid is a great pickup- I have several...the wiring diagram you need is here (keep in mind that our pickups and Fender's are out of phase): 

Ignore that it is a single coil-size humbucker...regular humbuckers are wired the same. 
Dave @ Seymour Duncan