Oh my goodness, Albirdo Hotwings is the best name ever! I love it! Do you have pictures? We'd love to see some.
As to your two questions-for the first, it would help to have more information. When does he bite? What does he get aggressive about? It could be a lot of things, ranging from hormones to territorial behavior to simple miscommunication about what his body language is trying to tell you. Does he get aggressive with everyone? Is he trying to guard something?
About getting another bird, I am of the opinion that getting a bird to keep your bird company is a bad idea. If YOU want another bird, then that's different, but if you're just thinking of Albirdo then it's a no. As long as he's getting enrichment and socialization from you it's not an issue, and there's just so many ways it could make the situation worse. On one end of the spectrum, he could indeed bond with the other bird and decide he doesn't need you. On the other end (more likely for parrotlets, tbh) he could decide he hates the new bird and then you would have to keep them completely separate to avoid fighting.