@OP: for starters, page count is irrelevant in the publishing industry where manuscripts are concerned; they count by words. In the print world standard novel length is between 80,000 and 120,000 words. Over 120,000 words and the strength of the binding starts to become an issue, according to what I've heard.
Every word processing software has a word count function.
For e-books, as far as I can tell most sites don't really care about length. I've seen 15,000 word porn shorts and 200,000 word epics on Amazon, so I wouldn't sweat the length. Like everyone else says, just write it out and see.
If you want to publish on Amazon.com, you can look up their formatting requirements and such on their website and set your word processing software to format the document that way.
I highly recommend doing this, because doing it manually on a work of any
length after the fact is a gigantic pain in the ass.
But the formatting rules for a manuscript document are pretty simple.
edited 2nd Mar '13 10:48:45 PM by drunkscriblerian