Well, hopefully I can answer these to the best of my ability.
1. There wasn't really a specific layout, except Gum Drop on the original version was almost always the first obstacle. Same with (New) Lake Double Dare on the Family versions. On the original Double Dare, virtually every run was done in a snake-like pattern with a different starting point (which is why the Sundae Slide was often the first, third or sixth obstacle). Most of the runs from Super Sloppy Double Dare onward had the courses run clockwise or counter-clockwise on stage with a way to accommodate for one or two in the center (they'd often start or end there).
2. Pick It was used only one known time as the first obstacle, on Double Dare 2000.
3. For the more prominent name changes...
Cold Fish became Sushi late in Super Sloppy Double Dare.
The Big Kahuna became Waveslide, Time's Running Out became Hour Glass, Hunt and Peck became Typewriter, Mt. St. Double Dare became Volcano and Thar She Blows became Horn Blower on Family Double Dare's 1990 season.
Down the Hatch became Mush Mouth, Dallas became Pipeline and Pick It became 'Da Nose in 1992.
For Double Dare 2000, the Sundae Slide became either Just Desserts or The Big Scoop depending on which version was used. Also, Mush Mouth was renamed Big Mouth, Pipeline became the Baked Alaska Pipeline, Das Blimp became The Blimp, Garbage Truck became Dump Truck and the Wringer became Kid Squisher.
Icy Trike is a special case. It was renamed Brick Wall when bricks were added to the obstacle in the Super Sloppy and Family versions. The original name returned for the first FDD season but changed back in 1992
Monkey Bars was called Just Hangin' Around for a time on the original version.
Toejam was briefly known as Foot Locker and Ant Farm was briefly known as Kid Farm.
