How close do different types of blueberry bushes need to be for cross pollination?
They should be planted within 10-20 ft of each other for cross pollination.
Do blueberry plants last over winter if they are left outside and are not watered?
As long as they are in the ground, most likely they are fine. Plants need far less water in the winter than in the summer and the ground normally holds more than enough to keep them alive.
The issue I see could be that without snow, the plants may not have had the insulation they are accustomed to, and that can hurt the plants. If you fear the plants may be dead, this article will help you tell that:
I have three blueberry bushes. One (the smaller of the three, about three years old) produces a few berries. The other two (four years old) have never had a berry on them. I'm about ready to dig them up and start over. Any suggestions?
What are the varieties? Blueberries grow best when they cross pollinate. If you have all the same variety, they will not produce well.
My Japanese blueberry has a lot of red leaves. Is this normal or is the plant lacking in water, fertilizers, etc? The plant is one to two years old.
Since there are many reasons for this and I cannot see for myself, here is a site that you may find helpful: http://www.fruit.cornell.edu/berrytool/blueberry/leaves/BBphos.htm
I have new smaller bushes growing under my blueberry bushes and I question whether or not they are actually new blueberry bushes.
They do not typically flower before putting out leaves. Beyond this, new bushes only a year old would likely not bloom the first year.
How can I protect the blueberry bushes from birds?
This article will help you:
Why does the new growth on plants that are about one year old turn brown in just 2-4 days ?
This sounds like a fungus, though it is hard to say which one as there are several that can cause this. I would treat the plant with a general fungicide and this should help to clear up the problem.