Can of worms... but ok, let's try to help.
-SH vs TB: objectively and logically, they'll always exhibit slightly different ratios on various factors - resistance relatively to inductance values won't be the same, location of E strings relatively to the pole pieces and of the pole pieces relatively to bar magnets will differ as well... not to mention that coil geometry will be slightly altered.
But the tonal effects of such differences are subtle enough to be felt as inexistent by people playing under high gain, for instance. And for questions of materials + evolving production methods, two regular spaced SH1's from different decades might appear ar less close tonally than a 59 and a Trembucker built the same week...
-CAN the magnetic field of a pickup affect some other pickup(s)? Absolutely. Anyone able to measure electrically induced harmonics will see their amplitude and locations changing while the height settings of ANOTHER pickup are modified (!)... It's counter-intuitive enough to have not been noticed much but it's there. Now, again, it's tonally subtle.
So subtle that I wouldn't base a personal choice on such parameters, TBH . But YMMV. Do what you want and be happy...
EDIT- OK, I'll confess... I don't like much trembuckers / F-spaced P.A.F. alike models and prefer the tiny wee bit of added warmth noticeable with trad Gibson spaced coils. But nobody is forced to be as anal as I am. <:0)
