Re: Two seo questions
There are probably a billion different theories and views on this depending on who you believe is up to us all!
Personally I optimize every page, however, the index page is the most important one. SE normally ask you not to submit more than the home page as the rest will get picked up along with it.
Not sure about the second part of your question, I have sites that are only of any use to UK customers only, and they end .co.uk, yet I have on my stats hits from russia, ethiopia, usa, NZ, outer mongolia, mars etc etc
Don't aim for success if you want it; just do what you love and believe in, and it will come naturally.