ipv6 question

[Michael Casey <michaelcasey73 gmail com>]

Hi

I just want to ask one big question :)

If I would have
an IPv6 address [home pc, behind a router - supporting ipv6 e.g.:
openwrt, ISP gives ipv6], then I can see an IPv6 address with ifconfig,
on the PC e.g.: "Z"
So that's my "very unique address". - "Z"

Can that be "seen on the internet", the "Z" address? so anyone can ping me from outside, or do an nmap?

Or
are there private addresses what the router gives to my pc.: eg.: with
ipv4 a router could give 192.168.1.10... and that IP couldn't be
pinged/nmapped from outside (More Secure???)
Because I heard that there will be no NAT with IPv6?

What
will happen to e.g.: a windows xp pc using IPv6? The "C$, D$....
shares" will be visible to anyone if they know the password?
sorry for the trivial question... :S :) and thank you for any answer