When you become a shaman, does it means that it can heal others?

No, every person can help and easy pain of other people. Man do not need be or become anything to do that.

When a person is doing "shamanic work" it do not always mean healing work, but finding information, which helps client to find peace in himself.

I am not sure if there is those times, when "shaman" actually in person heals anybody, cause usually shaman is just a vehicle, which spirits use. And being a vehicle means much more than healing somebody. Spirits may use you/may be used for a lot more of things. And, yes that way becoming shaman will provide means to ease pains of others.

jusma is right you make your self hollow boned so all spirits healing can pass through you and can be guided to where it is needed as jusma said you just make the conection not the healing