It depends on which one you order — the Grilled Chicken Sandwich has around 350–380 calories, while the Spicy Chicken Sandwich runs closer to 490–510 calories, and the Homestyle/Crispy Chicken Sandwich sits around 540–570 calories
Generally, yes — Wendy's chicken tenders (often called "Tendys") are well-regarded for being made with all-white meat chicken, a crispy breading, and a lineup of dipping sauces to go with them. Many reviewers rank them among the better fast-food tender options, though as with most menu items, opinions on taste can vary from person to person.
No — Wendy's nuggets are not gluten-free, as they contain wheat in the breading.
Yes — Wendy's nuggets do contain dairy (milk-based ingredients are in the breading/batter).