It varies depending on the dictionary you consult. Because it's derived from the proper noun World Wide Web, it started out as two words with Web capitalized. Webster's dictionary still lists it as such. Oxford dictionary lists Web site first with web site and website as variations. The American Heritage dictionary lists it as website with Web site as a variation. In everyday usage, website is far more common. You could defend either spelling, but for formal circumstances (like a school paper), Web site would be the safest.
Factbook is one word. Both on the website and offline.
both website and web site are correct; website is used more frequently
Two words - "one day".
They are two words conjoined to be one.
It is two words. Writing it as one is acceptable in the UK and is referred to as a "Britishism." But in American grammar, it is always two separate words.
It is two words take it from a 7th grader
"After school" is typically written as two words.
I recommend class work, as two words.
The term "in touch" is considered to be two words.
It is two separate words.
It is two words.
Two words.