Heat oven to 350° F. Toast the hazelnuts on a rimmed baking sheet, tossing occasionally, until fragrant, 10 to 12 minutes. Let cool slightly, then rub in a clean dish towel to remove the skins; coarsely chop.
Toss together the hazelnuts, tomatoes, basil, vinegar, 1 tablespoon of the oil, and ¼ teaspoon each salt and pepper in a medium bowl.
Heat grill or a grill pan to medium. Once it is hot, clean the grill grate with a wire brush. Just before grilling, oil the grill grate or grill pan.
In a second medium bowl, toss the zucchini with the remaining tablespoon of oil and ¼ teaspoon each salt and pepper. Grill the zucchini and bread until the zucchini are tender, 4 to 6 minutes per side, and the bread is golden and crisp, 2 to 3 minutes per side.
Dividing evenly, spread the bread with the tapenade and top with the fontina. Grill, covered, until the cheese is melted, 1 to 2 minutes. Top with the zucchini and serve with the tomato salad.