Those bloodline charts are always nice. I liked seeing the remnants of Phantom Blood on that page as well. That being a manga that stuck with me makes me appreciate this direct connection more than I probably otherwise would.
Joseph came to get Jotaro because it seems he is linked in fate with Dio! The Joestar’s have a star birthmark and Dio survived by taking Jonathan’s body for his own! If I recall, that was his original plan, he wanted to merge with Jonathan and Jonathan fought him off. However, it appears after many many years, Dio actually won. Although that could be argued. As he was reborn, it was stated that the stand in Jotaro was awakened. Something unlike Avdol who had a stand his entire life. As for Joseph, he achieved a stand a year ago! As everyone was anticipating what was about to be seen, I thought it was going to be a joke. He shattered a camera with a thorny strike and it was literally spirit photography, snapping a picture of the shirtless Dio where he was and transporting it back. How ridiculous!! It definitely got a laugh out of me, it’s pretty useful if not for the 30,000 yen requirement per camera smash. Dio has caught wind of all of this and has already begun making his moves.
One of which could be the attacker at the school, unless it's a red herring, maybe he's just jealous. He was able to paint a picture of Jotaro and use it as a painted voodoo doll, striking his legs and making him topple down the stairs. Big fire birds, big strong spirit men, spirit photography, and painted voodoo dolls, the powers in Stardust Crusaders are definitely different from each other.
Lastly, seeing all the girls fawn over the bad boy who just wanted them to leave him alone, it gave me the impression that, while having a good heart; Jotaro also seems evidently antisocial. Unlike Joseph who quickly befriended Smokey, or Jonathan who had a best friend in Danny and tried to be friends with Dio, later becoming close with his gang, Jotaro hasn’t actively seemed to enjoy spending time with anyone. Rather he tries to scare them off. Maybe outside of that smirk he gave Avdol which, with his antisocial behavior, may suggest we have a gruff, tough tsundere on our hands.