GMAB,
Regarding the first argument, I do believe that the world and all of its living creatures was created for people, to enable us to serve Hashem, so it’s approppriate for people to use the world’s resources to fulfill this task. This can, in my opinion, include eating moderate amounts of meat, and in my opinion definitely includes the use of animals in medical research.
As humans, we are told not to treat animals cruelly. Also, we humans have the responsibility to use the earth’s resources wisely and do what we can to preserve them. This is a simple application of the mitzvas lo ta’aseh of “bal tashchis”, not wasting.