First time grower, Golden Larch advice

[LostManAbroad]

I need some advice as I notice that my bonsai is changing colour. I want to make sure that I am not doing anything wrong. I have been watering it every time that I can place my fingers on the soil and feel no moisture then I water it until the water is coming out of the bottom. My question is about the change in colour. Is it simply due to the time of year? The man in the bonsai shop told me that this was an outdoor bonsai so it is on my balcony. My balcony is pretty sheltered from the wind. My other question is does the plant stay outside all year? I ask because Berlin can sometimes have pretty bitter winters. A few years back we had a straight 6 weeks of snow. Is there anything I can do to protect it while still leaving it outside. My apartment is pretty warm.

Oh, and one unrelated question, the tree already had the wire on it when I bought it. The guy in the shop did not give me any advice about how long the wire should remain on it. I'm always checking to make sure the wire doesn't cut into the tree. There were a couple places on the tree where that happened before I bought it. I want to know when it would be okay to take the wire off.