Train tickets for Tokyo travel

Hello. I'm a little confused about something, if anyone could help me, that'd be great.
We are planning a 2-week trip to Tokyo. We'll just be in Tokyo for the entire trip. I noticed the JR Yamanote Line goes to most of the places we want to visit. So, we were thinking about getting the Tokyo Free Kippu everyday (lots cheaper than a JR Pass).
My question is about the description of this ticket. This site says that it's good for Toei/Tokyo metro subways and all JR Trains in CENTRAL Tokyo. So is this ticket not good for all of the JR Yamanote Line? Or is the ticket good for all of Tokyo? The "central" part is concerning me, and making me worry that the Tokyo Free Kippu wouldn't let me use all of the Yamamote Line.
Also, if one was to use this ticket, would a person just buy one everyday at the ticket counter at the train station they'll be using? (We'll be using the Sinjuku Station the most)
Thanks!

The Tokyo Free Kippu is overprized! Most visitors to Tokyo travel cheaper by paying for single tickets than to pay over 1500 yen for a single day of Tokyo transportation!

In order to avoid purchasing single tickets for every single train ride, I recommend to use a Suica prepaid card, which is valid on all trains and buses in the greater Tokyo area except shinkansen and express supplements.

I agree with Uji- you are unlikely to spend anything like 1500 a day on JR trains within Tokyo- sure it is cheaper than the JR pass, but that is because the JR pass is intended for long distance inter city travel by bullet train, which is very expensive otherwise.

If you buy single tickets (or use a Suica card) you probably won't spend much more than about 700-800 yen a day, and you will also have the freedom to use the subway lines, which may be more convenient for your destination than the JR lines.

Spending 1,500 yen a day on a pass would be a huge waste of money.

I am actually in Tokyo,
You can buy the so called
"Tokunai Pass" from JR, this
pass costs Yen 730,00 for one day and You can use all the
JR Lines from Kamata to
Akabane and of course all of
Yamanote Line. Dont buy the suica.

Thanks for the help, everyone. Now I have a question about the Sucia pass. The site says it's provided through JR. So I just wanted to verify: you're able to use it on JR and non-JR trains AND on subways? (If not all stations, is there a site-or link on this site-that tells you which stations don't accept the Sucia Pass?)
And you use this card rather than buying tickets? That sounds convinient! I also saw on the page that there's a Sucia & NEX package available at the Narita Airport. That sounds like a great deal, too! (Sorry if I'm stating the obvious, but I've been trying to figure out transportation in Tokyo for a while now, and I might finally be getting it!)
Thanks again :) I appreciate the help!

You can use SUICA card virtually at any JR line, Private Railway line and Subway line in Tokyo and Yokohama area. NEX & SUICA package is a good deal.