Ask yourself this: why did you take their pictures and why do you want to photograph street people? Do a search on this lady : Moyra Peralta. When you THINK you know why you want to pursue this field, figure out if your motive is altruistic, artistic or parasitic? You don't have to justify yourself to anyone, just your own conscience. Wrt the longer lens, I have found with "street" shots Capa's saying bears out: "If your images aren't good enough, your'e not close enough". So ditch the tele zoom idea and get in close.
I'm not looking to give you a hard time or get preachy. I've photographed homeless people, they feature on my website, then I read about Moyra Peralta. That's where balkancing your urges with conscience comes in.
Cheers, Lol