Greetings!
These are actually some very smart questions! The internet is new enough that citation has not become completely standardized. It also depends what citation style you are using (MLA, APA, Harvard, etc.). However, you obviously cannot use page numbers where none exist, so some citation styles recommend a paragraph number or a section number, if the site has numbered internal divisions. You can use the ¶ symbol or, instead, the abbreviations chap. or para., wherer applicable. If there are no division like these on the page, the author's name will have to suffice.
I hope this helps!
Thanks,
Sarah, EssayForum.com
Sarah, EssayForum.com