Fishbone,
The worst thing you can do is put your Juniper Procumbens Nana, is inside a house or office. Although you can do it, but only for a short period of time, the less the better. Your baby Nana would rather be left outside year round. Being you live in Nebraska, it will be impossible to leave outside. Your Nana shrub, known as a "whip" should be left outside as long as the tempature is 40 degrees or above. If it gets 39 degrees or lower, it needs to go in a closed garage with the pot wrapped with insulation. As soon as the temperature gets back to 40 degrees it needs to go back outside and away from wind. If during the spring and throughout summer to earlie fall your nana starts to turn yellow, you will need to give it liquid iron, every 4 to 6 weeks is good.
Here is a video that will prove what they told you about watering is totally false.
http://www.bonsaichannel.com/mrBonsaiWizard1.html
Here is another link from the bonsai channel that may help you with other questions. They cover all aspects of bonsai.
http://www.bonsaichannel.com/
Have fun