The N7 LO is great, moreover with its pre amp mode. So it’s rather a good idea if the fact of having an amp to carry doesn‘t bother you, it’ll elevate N7‘s sound.
They are all 3 great with different qualities, you should read the different feedbacks on the
Watercooler thread or each amp dedicated thread and reviews to learn more about (and also Twister6 reviews
here and
here).
Yes but not as much as changing your IEMs for others more suiting your taste imho.
Its a different taste, but not as much tube sounding like a desktop tube amps could be b.e.
It colors a bit the sound but not too much, you could also read more precise feedbacks on C9 thread and
reviews.