During the missions Special Delivery and The Secret of Cabot House, some choices may lead to me being given a Mysterious Serum. Is it possible for my character to become addicted to using it?
On a side note, Nick Valentine dislikes it if I open Lorenzo's cage, but is that all he dislikes in the mission, or will he permanently have some sort of hate against me if I let Lorenzo loose?
The Fallout Wiki says that you cannot get addicted to it (under the picture).
Also, under the notes section:
Though the in-game consumable is not addictive for the player character, the Cabot family are psychologically addicted.
For the Nick Valentine part of your question, see this answer. He shouldn't permanently hate you for doing that (there is no mentioning of it on the Wiki pages), but his affinity will drop.
