Are the rewards for buying and exchanging copies of the Qur’an multiplied, and does one who brings a copy of the Qur’an for another receive the reward for the latter's recitation from it?

There is no explicit text from the people of knowledge regarding this issue, but it appears that each of you will be rewarded for your intention and purpose. It is hoped that reward will be obtained due to the other person reading from your Mushaf, out of Allah's vast grace. Handing a Mushaf to another person for them to read from it is rewarded because it is a form of cooperation in good deeds, in accordance with His (the Most High) saying: "And cooperate in righteousness and piety," and because "the one who points to good is like the one who does it."