post visiblity

I want configure a private wp in such a way
that 1)its visitors will be able to post and see
their own posts only but 2)will not be able to
see posts posted by other, 3)admins can see/
modify these posts and 4)I want to do this for
CustomPostTypes also how to achive these
things ?

http://ww.wp.xz.cn/plugins/s2member/