Place potatoes in large saucepan with cold water to cover by 1 inch. Bring to boil over high heat, add 1 teaspoon salt; reduce heat to medium-low and simmer until potatoes are tender, 10 to 15 minutes.
Drain potatoes thoroughly, then spread out on rimmed baking. Mix 2 tablespoons pickle juice and mustard together in small bowl; drizzle pickle juice mixture over potatoes and toss until evenly coated. Refrigerate until cooled, about 30 minutes.
Mix remaining tablespoon pickle juice, chopped pickles, remaining 1/2 teaspoon salt, pepper, celery seed, mayonnaise, sour cream, red onion and celery in large bowl. Toss in cooled potatoes, cover and refrigerate until well chilled, about 30 minutes. (Salad can be refrigerated in airtight container for up to 2 days.) Gently stir in eggs, if using, just before serving.