A few questions...

Hi there, I'm considering getting a parrotlet, but I have a few questions that I've had difficulties finding answers to.

First of all, I've heard that they can be very aggressive and even kill eachother. Yet a website recommended buying them in pairs to ensure that they won't get lonely. I'm not sure what to do here. I'm afraid that buying two, will end up in one killing the other (through jealousy for example), but buying only one may end up in a lonely bird. What is best?

My second question: I don't want to clip it, but I don't like the idea of keeping it indoors for the entirety of its life. Anything I can do here?