Ethics in research on the internet

This is a series of questions in an area where I'm trying to work out what my position should be. These questions arise from asking whether we should view the internet as a collection of public and private documents, or as a collection of interations between people when it comes to doing research with the material we find there.
First Question Can I use posts to an online comunity of practice as objects of research without the consent of all people concerned? Probably not. Unles all posts are pubicly visible and are made in the expectationnthat there is a large body of public lurkers following the postings, I dont think one can. In this circumastance I think there is an expectation that this is a shared but not nescescariy public conversation and that materail posted is for the purpose of contiuing the conversation.
Exceptions to this expectation of privacy, would be overwhelming public interest i.e. it is for the public good, or where respecting the privacy of the context would be tantamount to coluding in a criminal act.
An example of this type of interaction maght make this clearer. There exist online discusion boards for profesionals in the drilling industry, While members of the press might join such boards to get deep background on a drilling rig acident, it would be inapropriate to quote statements made in such a context with atribution. The public interest here is that profesionals need a forum for rapid and open discusion of technical issues, impeding such discusions is not in the general public interest.
Second Question Can I use material from a freely available newspaper article, displayed on the web for academic research? I think I'm on safe ground here in saying yes, and no further permision is required, unless there is an issue of either plaigarism or copyright. I.e. I cant misapropriate the ideas without atribution, and I cant quote the material to such an extent that it becomes tantamount to republishing. (This is the 10% editorial use rule).
Third question, and this involves the issue of informed consent. Supose I join a racist organization and become part of a private online discusion, the content of which I consider as being of acedemic interest. Here I think there is not a hard and fast line. If there are criminal matters invoved, then I think my duty to avoid colusion in crime alows me to break confidentiality. However I think as we move away from the criminal context, the distinction becomes less and less clear cut.In general here is where we get the distinction between thetwo modles. The "A collection of Documents" view point tending to allow, while the interations between individual people is significantly less liberal.
Any thoughts?