The citing commands of biblatex feature a second optional argument that does what you want. Note that if you only want to add a citation prenote, you have to use both optional arguments (with the postnote argument empty).
\documentclass{article}
\usepackage{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@misc{A01,
author = {Author, A.},
year = {2001},
title = {Alpha},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
See \autocite[99]{A01}.
See \autocite[e.\,g.][99]{A01}.
See \autocite[e\,.g.][]{A01}.
\printbibliography
\end{document}
According to The Chicago Manual of Style, the purpose of citation is "ethics, copyright laws, and courtesy to readers." In other words, not only in the case of technical papers, citing a paper/article/book/etc. after providing some information has two meanings: (1) I (an author) have not taken the information out of thin air and (2) dear reader, if you want to know more about the presented information, please look at the cited work.
Taking this into account, @misc you (and Michael Shell) have presented is enough and complete. Generally, there is no point in citing exactly the communication channel. Does it make a difference for readers if you say that you have exchanged letters with Dr. X or have spoken to Prof. Y during the 13th IEEE XYZ Conference? I'd say no.
The above-mentioned citation leads readers to the source correctly. If a reader wants to know more, he/she should contact the cited person. Since he/she cannot use a time machine to go to the 13th IEEE XYZ Conference, there is no point in citing a venue. If Dr. X answered you a letter, he will probably answer an e-mail from a reader or respond to a direct question at a conference. Thus, the conversation channel is also needless. Such a citation is also correct from the copyright and ethics point of view: it says "it is his/her idea."
If you have been exchanging a lot of information via different channels for many years, just use 1998--2010 in the year field. In many cases, an "one person = one reference" rule will be enough (note, that you can always cite a reference many times in your work).
Best Answer
When citing online sources, I was taught to cite at the very least the authors of the web page, the URL and the date the page was created. For a Youtube video, this might be the name of the channel and the date the video was posted.
An important addition to any web citation is the date you accessed it, as unlike print resources, webpages can change over time and the person reading your bibliography may not see the same information as you did at the time of citation.
For web resources, this is how I format my BibTex entries:
which looks like this
(blue hyperlink made using the hyperref package)
There are probably neater ways of doing it, but using the
@miscmeans you can choose which fields you wish to enter. Your particular institution or assessor may demand additional information in your bibliography, so you can easily add those using this method.