Part of your problem comes from braiding too loosely. This is very common and usually results from people who are afraid of stretching the dough too much. Don't worry about it. If your loaves get too long, make your braids fatter next time.
I think four or five ropes work better, and results in a more elegant look. Of course, that's a matter of taste. The structure will hold the ropes together in the braid and force you to braid tightly. You might try that with your next effort.
Something else to try is starting your braid about 1/3 of the way up the ropes, and braiding in both directions. This should put the thickest part of the braid in the middle of the loaf, while the stretched out ends can be hidden. You won't end up with a one end substantially thicker than the other.
Once you've got one of the braid styles working, you'll have the "feel" to make the other one work as well.
Vo den? Not to mention, "Aha!" Soft and sticky is generally a good thing for most breads. Rule of thumb and all. Challah? no.
There are a lot of ways to skin the challah cat. The most common style is a fairly stiff dough. Use just enough water to bring the dough together, and then start adding flour until it won't take any more. Note: This type of dough is too stiff for a mixer, and will have to be kneaded by hand. Knead it well, young padwan.
Speaking of kneading ... I forgot to ask, but over or under kneading could be the problem. Knead to the windowpane stage. No more, no less.
Let's talk variations: I like to use a slightly stiff dough with a lot of oil, margarine or butter. Enough to give the soft dough a slightly slippery feel. This is not the most common style of dough, but it's a good one. I use 8 oz of butter per 7 cups of flour -- and that's a lot of butter! In fact, it's double compared to most recipes. Of course, if you keep kosher, you'll want to use something pareve like margarine or vegetable oil. If you do use margarine, avoid the new "0-transfat" types. Although slightly healthier, their baking properties are very poor. If you don't keep kosher, use butter. Big improvement. In fact, "like buttah."
In any case, the dough should be stiff enough and kneaded well enough that you don't need much extra flour to make or handle the braids. Some, to make it easier? Okay. A lot because otherwise it sticks to the board and can't be braided? Not good. Your dough's too soft. This ain't coffee cake.
As long as you're not leaving them loose. Still, you might want to try folding the pinch under. You'll lose a little of the braid effect at the ends of the loaf, but keep a tighter braid. The final look is very nice, with the braid seeming to raise out fo the loaf rather than extending all the way to the end. If you think about it, that's the look you see with professionally made loaves -- now you know why.
aka the final rise. You're probably doing it right, but I've gone too far to stop nudging. Try not to let the clock rule you. You want 2/3 of the total rise after braiding to be at low or room temperature, and the last 1/3 in the oven.
Your 325 bake is fine for a very soft, shiny crust. Most challah are baked at around that temp. 350 will give you a more definite texture with just a bit of crackle and chew. You might want to try it some time down the line. Or not.
I'm assuming you speak Eskimo. Zol zion mit mazel,