You have a hybrid that is said to be very hardy and tough. Clearly, it's living up to its billing :)

That's going to be one rootbound rhododendron. I'm assuming you are planning on putting it in the ground? I think the first thing I'd do it submerge the pot in a bucket or tub, make certain the rootball has become completely wet....the roots will surely prove to be so dense and matted when you take it out of the pot, that will be easier to do before you install it in the ground.

I'm also sure root pruning will be necessary. With a SHARP knife, cut an inch of matted roots from the edges of the rootball. Put the watered, root pruned plant into the ground, making sure you are planting no deeper than it was growing in the pot. Mulch the root zone after planting - am I seeing a gravel mulch in your beds? For this plant, I'd rather see something organic, ground bark or even better, compost.

You're going to have to watch this one carefully until Fall rains start and it has had a chance to establish roots, make sure you are watering at the base so the rootball gets moist and not just the surrounding soil.

For having spent that many years in the same pot, it could look a lot worse - Without examining the roots myself, I see no reason this shouldn't begin to look healthier after a few weeks planted and could live a long life in your garden.

How long do I soak the root ball for? The soil in that pot, if it can even be called soil anymore, is very hard, almost cement like.

That's actually pine shavings I have as mulch so, good on the organic mulch.

Also, along with the root prune, should I prune the canopy or just leave it until next year?

Soak until air bubbles stop rising, you will probably have to hold it down to keep it from floating initially. 6 hours maximum, you don't want to leave it submerged overnight.

You could prune any dead stubs - there doesn't seem to be that many. I don't see anything to be gained by pruning the top growth on your plant. Rhododendrons don't require regular pruning, and it's healthy roots that will establish into the ground that you need to concentrate on now.

I agree with everything morz8 recommended. I have a different style of opening up the roots. I run a sharp box cutter down the outside of the root ball about every 2 or 3 inches. Then do the best I can to open up the root mass and spread it out. Make sure none of the larger roots are crossed. If they are, remove one so they don't grow into each other. I have a friend who goes after the root ball with a claw like tool to open it up.

It should do very well for you. It is a great variety for your area. I have several in my garden.

Here is a link that might be useful: How to grow rhododendrons and azaleas.

After the soak, should I remove most/all of the crap soil from the pot and basically make this a bare root rhodie or should I just cut up the outer inch and plant it with the crap soil intact?

I doubt if you will find much of the original potting medium left - I suspect you will be presented with a serious mass of roots to deal with instead. Barerooting isn't your goal as much as freeing some of those entangled roots so that your plant can begin to establish out into the soil and take up some needed nutrients that will be available there.

Also, cutting away an inch of roots is not a goal either. Opening up the root structure is the goal. The cuts are not to remove roots, but to open up tangles.

Make sure you get it planted and watered before the roots dry out. If they dry out they will die. They must be kept moist.