Combine first 8 ingredients in heavy 2 1/2-quart saucepan (about 3 inches deep). Stir with wooden spatula or spoon over medium-low heat until sugar dissolves (no crystals are felt when caramel is rubbed between fingers), occasionally brushing down sides of pan with wet pastry brush, about 15 minutes.
Attach clip-on candy thermometer to side of pan. Increase heat to medium-high; cook caramel at rolling boil until thermometer registers 236°F, stirring constantly but slowly with clean wooden spatula and occasionally brushing down sides of pan with wet pastry brush, about 12 minutes. Pour caramel into metal bowl (do not scrape pan). Submerge thermometer bulb in caramel; cool, without stirring, to 200°F, about 20 minutes.
While caramel cools, line 2 baking sheets with foil; butter foil. Push 1 chopstick into stem end of each apple. Set up decorations and melted chocolates.
Holding chopstick, dip 1 apple into 200°F caramel, submerging all but very top of apple. Lift apple out, allowing excess caramel to drip back into bowl. Turn apple caramel side up and hold for several seconds to help set caramel around apple. Place coated apple on prepared foil. Repeat with remaining apples and caramel, spacing apples apart (caramel will pool on foil). If caramel becomes too thick to dip into, add 1 to 2 tablespoons whipping cream and briefly whisk caramel in bowl over low heat to thin.
Chill apples on sheets until caramel is partially set, about 15 minutes. Lift 1 apple from foil. Using hand, press pooled caramel around apple; return to foil. Repeat with remaining apples.
Firmly press decorations into caramel; return each apple to foil. Or dip caramel-coated apples into melted chocolate, allowing excess to drip off, then roll in nuts or candy. Or drizzle melted chocolate over caramel-coated apples and sprinkle with decorations.
Chill until decorations are set, about 1 hour. Cover; chill up to 1 week.