well its tricky task and doesn't worth the time and efforts if you want to accomplish this with httprequest or any other C# client. however, you need to bear in mind all of the stated facts are based on "imaginary" thoughts so you don't need to get into that road, coz you will end up thinking more than working which means = wasting your time. and eventually you are not gonna figure out what google is actually using to detect bots.
but if you really want to do that you can actually use a simple webpage control to download the page for you. all you need is to parse the innerHtml and that's it...