First time in another country (Spain edition)

ok guys, so I'll be going to Benidorm, Spain, sometime in July with family (my father booked the cheapest flight and hotel he could find ) and I just wondered if anyone could give any advice on

What to do?

Where to go?

Allergen friendly food (gluten free, dairy free, halal)?

What phrases and things to learn in Spanish that could come in handy?

And just general advice for someone who has no clue about travelling (been too poor to fly, lol)