I have read the document you mentioned. It describes quite well about how Cache works in ASP.Net, but never mentions what impact will be for cache when we do online upgrade for the web site, also it does not mention impact to session during online upgrade scenario. Any more descriptions or more documents to make recommendations?
What do you mean "For session, it will be happen in the case of Session State inproc. But I think for SQL Server Session mode it will be available." -- more description please?