Yes :) I cannot see why you doubt it.
E = (1 / 2 π ε0) (λ / r)
Rewrite by multiplying the two fractions:
E = (1 λ) / (2 π ε0 r)
Multiply with the denominator on both sides:
2 π ε0 r E = λ
2π r ε0 E = λ
Compare to the other formula:
q = 2π r L ε0 E
In this, divide by L on...
If it was me I would probably weigh an egg, and figure how fast it is going after falling 7 meters. It should offer some clues as to the momentum the device is required to absorb. Ignoring air resistance will give a higher estimate, if that proves unrealistic you can probably get pretty close by...
Your first question seems to have gone unanswered. Yes gravity is an inherent feature of matter.
Anything with a mass will have a gravitational influence. Before Newton, gravity as a concept was not very well understood, it was not clear that astronomical objects moved the way they do due to...