Alright, WTF! The map indicator points me near Stendarr's Beacon, to talk to the Dawnguard learder, but he, she or it isn't there. And, no one at Stendarr's Beacon knows squat. Can I get a little assistance here, please? How do I get this DLC started, so I can get on with life?

There's a cave near Stendarr's Beacon. Follow the quest markers.

I found it, but I can't play it. Every time I try to enter the door of the Fort it starts to load then the game crashes to the desktop. Apparently I spent $20 for nothing.

Quest markers are useless in this case. I ended up using Clairvoyance to find it the first time.

Hmmm.... Do you have or have you ever had a mannequin mod?

Yes to the mannequin mod. I went into TES and unchecked all of the .esps. I restarted the game and found myself inside the door of the fort. However, I had no hair nor the armor that I was wearing. My companion was fine, however. I then went back in and rechecked the esps. trying to fine the issue. Each time I restarted the game--which incidentally was about ten times--I found my character still inside the door of the fort, but again bald and naked. That said, I opened up the console and typed in "showracemenu" and while I could replace the hair style that I was currently using it was clipping over the "very sixy Ebony Armor," that I had in my backpack. The hair mod that I use is the "Apachii Sky Hair."

Now, I will go and delete the mannequin mod. I let you know whats happened.

It was the Mannequein mod

As it was with me. There is a mannequin in Castle Dawnguard that apparently didn't like the script.

To tell you the truth, I am not at all impressed with this DLC. It reminds me of the "Witch Hunt DLC" for Dragon Age Origins, which was an epic failure like DA2.