Wow bro…10% is pretty decent in terms of bypassing. Surprised that even with double springs it could get this.
Of coz, just gotta keep in mind that this would cause the kickdown to occur a little faster, but i think with a SBT 90.2 (5000+ lumens) in a 230 gram host still ought to be pretty ok / practical
Answer 1. Just test it out yourself, put it 3 inches away, 6 inches, 9 inches. It probably would vary just a little in most cases, not a big difference.
I know for my case here it wouldn’t matter much. But of course keep it at the same place for the same flashlight before/after mod.
2. Doesn’t really matter significantly…but do measure at just 1 location so that at least this is a constant.
3. There is a little variation unless if it really is a throwy light (eg your TS30S) vs a very floody light (eg X80-GT2), else not a big deal. The light sensor reads less if you hit it from the side, but it’s gonna be from quite an angle wrt the flashlight’s hotspot. Also think in terms of flash photography, if you angle it 45 deg, then of course the light is gonna be reflected away from the photographer, so it’s gonna be the same for an extremely floody light (Acebeam X80-GT2).
For these, really gotta put them into contraptions like pvc lumen tubes etc.
4. 5 feet is good, not much issue if it were 3 or 5 feet.
5. Yes, in range.
Regardless, it’s just something that you do it and be happy with it . Coz in real life, like what i have posted above before, things like whether or not our eyes are adapted to the dark and also how our pupils react to the hotspot/spill in different environments (target reflectiveness) would wash out any of these 10, 20% differences. That’s why experienced flashaholics would tell you all these small differences dont make a difference in reality. In fact we know that if we wanna upgrade, take for eg my 25k lumens OTF JKK76, it’s gonna be at least a MS12 mini, minimum. That’s if you really want to be a happy flashaholic. 
Or put it this way, i actually have 2pcs of JKK76 (1 is 6500k and the other 3000k), and also i can switch on 1pc and then the other in say setting 3, turbo etc. I’d say the above upgrade example of JKK76 -> MS12 mini is true, just on the lumens output aspect. Other than the turbo setting on the 2nd pc, all other settings don’t really make much of significant difference and that is only coz if i were in the know that i am using/controlling the 2nd pc.