To find a mate, go to the fair territory and look for a pink rose! Then take the rose to a cat you want as a mate, the cat may reject you though.
Another way is pressing c + m at the same time. A bar you can type things into should pop up, when it does type love. It'll let you get pink roses when you press space! To deactivate it press the pop up in the left bottom corner :]\
About the cold stone vision. You'll need to first be a full medicine cat. If you don't know how-- You need to find Lunarclaw, Fireclan's medicine cat and then as her to be her apprentice- then go to Breezestar and ask to become a medicine cat. Go through all the stuff blah blah-- you need to heal 5 cats without asking Lunarclaw what herbs do to become a full medicine cat, you'll need to talk to lunarclaw once you've healed five cats. Once you do, go to cold waters. They should let you in now, to get the dream. You press on the moonstone and it should give you the cutscene-!
Oh yeah, if you press c + m [ at the same time ], and type in magic while doing the medicine cat stuff. You can press space to get whatever herb the sick cat needs!