I need to warn you that I almost always have follow-up questions.
Glad to see them. Just try to keep them simple, OK?

So--the next part of my question is--do Buddhist feel that something can be done to get rid of pain in other sentient beings besides humans?
Essentially all sentient beings are going to have pain-- that we simply cannot totally avoid. Therefore, it becomes a matter of can we reduce or lessen the incidence of pain. We can possibly reduce it physically and/or mentally, depending on what kind of pain we may be talking about. How animals are raised, therefore, becomes an important issue. A quick killing of an animal for food is probably far less of a problem than having the animal raised on a factory farm, where it's jammed in with others, and then must be given all sorts of medication in order to try and stop the spread of disease, which is magnified under crowded conditions.
Obviously there are other ways whereas we can help as well.
There are many species of animals that are self-aware--monkeys, many of the predators, etc.
Are these considered as individuals--or just in the general group of "sentient" but we're not going to do anything for/with them except refrain from eating them?
There' really both individuals and sentient. We humans, after all, are another animal. And, yes, there are things we can and should be doing, such as protecting and conserving their environment, animal rescues in cases of natural disasters, etc. But I say this not that we should be just focusing in on just other animals, but that much of what we do to help ourselves can also be used to help them.
Good questions, btw. Keep firing away.