I just received this beautiful Bonsai. But it didn't come with instructions on watering, or how much sunlight. I'm in New York and its freezing. I want to put it by the window because I get a lot of sunlight, but its cold by the window. Also the tree is very thorny and if you touch it. needles easily fall off. What should I be doing for this beauty?
Before anything else, if you really want to keep a bonsai alive, I highly, highly recommend you invest in a good book on bonsai care. Something you can reference any time to help you get a feel for the plant's needs.
It's a Juniper. These can be kept as bonsai for 100's of years. It's winter, and the plant is dormant. It needs cool temperatures (45 Fahrenheit would be great). Water only when the top of the soil is dry, and only enough to dampen it again. Don't fertilize until the tree breaks dormancy. Light is good, especially filtered sunlight. As an evergreen, these need light even while dormant.
I'm concerned about how you mentioned the needles easily falling off. This can mean the tree is dead (even if it's not brown). Hopefully it was only older needles that were falling off, which is normal and happens yearly.
Again, please consider getting yourself a good guide.