I generally start with a 750-1000 word article on my home page and 4 500-750 word articles for secondary keywords. I then add 1 new post each week about related topic to keep fresh content coming in and also to target long tail keywords.

I don't think there is any magic number of pages to have, just try to post quality information and keep your site up to date.

Yes, Google actually cares.

Just keep in mind that when you create websites be sure its for Human not for robots.. there is actually no limits in words in each page or how many page do you have.. It is a matter of relevant information and completeness in your website(Title, Content, etc etc.)