Edit meta tags manually, without plugin

meta descriptions for each and every page

you basically cannot easily add individual meta descriptions to each page; there are no ‘physical’ records per page on the server, as these are done dynamically.

using a seo plugin would be the easiest option – http://ww.wp.xz.cn/extend/plugins/search.php?q=seo+meta+description

however, you can do something similar with a bit of coding added to functions.php of your theme, to use custom fields for the meta descriptions;

for static pages, and single posts, there is some example code in my article ‘Mini SEO – a Meta Description Field for Posts and Pages’

edit my meta description tags for every author and every topic?

does that refer to the archive pages?
this is not covered by my code, however, in these cases you might be able to utilize the category/tag descriptions and the author bio (?)

if you need further suggestions, please provide a clearer specification for what cases you need to have the meta description.