it means "How have you been" or "how have you been doing". It is usually used if you haven't seen a person for a while For example: If you haven't seen someone for a period of time (a few days, a week, a month, etc) you could ask: "How have you been getting on?" as a replacement for "How have you been?" I think this phrase sounds a bit more British English than American English. I don't often hear many people use it in America.

I think it means like if someone ask another one about his/her process or success. I hope I'll be right

It only means the same as. How are you doing, How are you. It is about the same as. 你过的怎么样