What causes my blueberry fruit to shrivel? What can I do to correct this?
This may signal a pollination issue. Without proper pollination, plants will normally abort their fruit/blossoms. If there are not enough natural pollinators around, the plants will have difficulty producing. This is why we sometimes have to intervene by hand pollinating. Just use a small paint brush and swirl it around the inside of the flower and repeat on all the flowers on the plant. You can encourage additional pollinators to the area as well. Here is more information: https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm, https://www.gardeningknowhow.com/garden-how-to/beneficial/creating-a-pollinator-garden.htm
I have a Chandler Blueberry, which is approx. 3 yrs old. It has only two stems and the top third has the leaves and fruits on. How can I, if at all, make the leaves grow on the top 2/3?
Pruning the plant can often help with getting them to fill out. Late winter or early spring is the best time to prune them. This article may be helpful as well: https://www.gardeningknowhow.com/edible/fruits/blueberries/blueberry-plant-pruning.htm
Typically how many weeks do mature blueberry bushes produce berries in North Florida?
There are so many cultivars of blueberries, it's hard to make generalizations, but I should think most of them bear for three to four weeks.
Blueberry cuttings possible?
Nurseries from which you buy blueberries have produced them from cuttings, but everyone says it's quite difficult for the hobbyist to accomplish. This article has basic information, plus a lot more: http://www.ces.ncsu.edu/hil/hil-8207.html
I found a separate growth in my blueberry bush barrels that seems to copy the blueberry leaves although the fruit is strange. A reddish flower with a single dark blue (droplet) fruit.
It's probably a sport, that is a branch that has reverted to the characteristics of a progenitor plant, or it could be a sucker growing from rootstock, if your plant is grafted. In either case, you can reach into the plant with pruners, and cut off the branch bearing the strange fruit where it emerges from the root or a larger branch. While you're here, an article on growing berries in containers: https://www.gardeningknowhow.com/edible/fruits/berries/berries-growing-container.htm
I didn't realize that blueberry plants need another variety to pollinate each other. How long will it take for the non producing bush to have blueberries? And do raspberry bushes also need another variety to pollinate?
Some varieties of blueberry are self fertile, and some aren't, so you need to find that out when you purchase a blueberry plant. However, there can also be cultural reasons why you're not getting fruit. This article will help you check on that: https://www.gardeningknowhow.com/edible/fruits/blueberries/growing-blueberry.htm
As for raspberries, most of them are self-fertile, but most people find planting at least two varieties brings in better fruit. This article has more information: https://www.gardeningknowhow.com/edible/fruits/raspberry/care-of-raspberry-plants.htm
I would like to know when to transplant my blueberries to my backyard from containers because I don't see them growing and this year I only get 6 blueberries.
There is nothing intrinsically wrong with growing blueberries in containers; indeed, some people prefer to grow them that way, to make sure they have the special acidic soil condition they require. There's a good chance that if you take care of soil, water, and light, your berries will grow, whether they're in containers or the ground. Here are some tips on blueberry growing: https://www.gardeningknowhow.com/edible/fruits/blueberries/growing-blueberry.htm
https://www.gardeningknowhow.com/edible/fruits/berries/berries-growing-container.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/raise-acid-level-soil.htm
If you still want to transplant, you might want to consider these basics: https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm