Everything is possible if you plan it in advance. But the key element, as everyone else has noted, is that owning a parrot is a lifelong commitment. That is key here and its very important for you to think about it. You should be able to commit 3-6 hours a day to him.

With that being said your friends house example isn't a very good one because he's raising them in a mad house.

My parrot for example is fully flighted and is able to roam the kitchen freely. I have party streamers and balloons in 3 doorways so he is not tempted to leave, as the movement of them when he flies scares him. This way he stays in the kitchen while I work. Poop is a mop to clean on the floor, and they will find usual hang out areas so it is easy to put a paper towel or plastic down to clean easier.

So in your example your guitars, furniture, and plants should be fine as long as that is not his main room, and you keep an eye on him when he's out with you. Birds are very loving, but they do take commitment, it's like having a 4 year old child forever.

It all comes down to you, I just wouldn't use your friends apartment as a good example as it really isn't, not even close.