1. Here are the regulations about character.
http://www.immigration.govt.nz/opsmanual/35052.htm Were you told that you were under any kind of prohibition or time-limit when your application was rejected? There are mentions of such things under A5.20.
2. No immigration adviser has any special pull with INZ. Applications from individuals have just as much right to success as those from legal agents. However, in your specific case, you might PERHAPS consider using an immigration lawyer.
3. If ever you apply for a visa to any other country, the fact that you were refused the previous application to NZ is going to come to light. You will have to declare it - if you didn't, it could come up through the links between different countries' immigration bodies anyway. No doubt you will have to answer questions about the circumstances, then the other Immigration will consider what to do.