Get the book by Charles Wells, it has a ton of photos and info. Remember most of the pictures/videos you see online are of the few hard obstacles on the trails. No one really videos the long boreing straight trails.
Most of the hard stuff has a bypass tight by it, so you dont have to do it unless you want.
What all is your jeep about? (I havent looked at your profile) If you are set up for camping/overlanding stuff, you might not fair to well in Poison Spider, on the flip side if you are full up on 60/80 rolling 40's, then you shouldnt stress it much.
Typically I would suggest you average 3 miles per hour on a trail. This will give you an idea that if the trail says 4 miles round trip, it should be 2 hours min, always konger with more people, slower ya go etc.
Tons of info on here, watch the videos. Enjoy it and take lots of pictures! I'm headed down in the morning for a couple days.