There is a buy-in in poker tournaments. It will depend on the buy-in you paid.
I'm not sure about the number of chips needed for a tournament. Facebook Poker chips and myspace poker chips at cheap prices are available at http://www.facebookpokerchips.co.uk
It depends where you are playing online or land based casino. Also it changes monthly basis some times on online sites.
It is up to you how many chips you want to buy to play Poker.
It depends on the number of players you plan to have in your tournament. You will probably a minimum of around 25 chips per player although I would plan more like 30 or more and you will need different color poker chips for different values. A 500 pc. set with the correct denominations would be plenty for a 10 person tourney.
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them