I believe so, the treatment dose is small enough that the physical stimulant effects are typically very minor, even for new users. I don't have numbers, but I recall that people abusing it for the stimulant effect use 3/4x the ADHD prescription dose, which results in very different effects.

Metabolism plays a big role in determining the effective dose.

There are people who can take what are considered high therapeutic doses and feel very little effects because of the way their body metabolizes the chemical, which of course has nothing to do with whether they have ADHD or not.

For sure. I take adderall and have an incredibly high metabolism to the point of needing to add 1500 calories per day in protein shakes to stay at a healthy weigh.

7.5mg (15mg in half) is my usual dosage, but it's strong enough to fill me with the energy you'd expect someone on a high dosage to have. When I talk a full pill, it completely screws me over. Others can take 30mg and be completely fine.

Maybe, maybe not. My education is not in biology or medicine, so I cannot really speak well on the dominant factors in how a drug affects any given person.