A stab at the meanings (although I can't figure out 4...)
#4. This one eludes me. It's a poem specific to a person (柳宗元) and location (永州), and refers to the loneliness of his banishment there, but I can't grasp the deeper zen meaning.
漢詩について。江雪 柳宗元の漢詩なんですが。山という山はすべて、鳥の飛... - Yahoo!知恵袋
柳宗元『江雪』 書き下し文と現代語訳(口語訳)/解説 / 漢文 by 走るメロス |マナペディア|
#5. I like this explanation
質問させて下さい☆「両頭截断すれば一剣天によって寒し」の詳し... - Yahoo!知恵袋
Coming to a fork in a road in which either path may lead to life/death or good/evil, and you do not know which road will lead where, the right choice is to choose neither (cut off both choices), and follow your heart/soul/conscience. Very zen. I like it.
#6.
http://members.jcom.home.ne.jp/s.kubota/zengo/sub5.htm
This one doesn't do much for me. Just as the Spring brings grass, and Autumn brings colored, falling leaves, the teachings of the buddha come to us in the course of our lives. We need not search far or long for them, or search for hidden meanings.
#7.
五文字 (17) : 書作品と漢語集
茶道|茶席の禅語
A bit elusive, this one. Something about how the clear water reflecting the trees is one with the mountains, just as the natural heart/soul of a person is one with buddhism.