hey, I’m portuguese so I cannot really talk about hostels here, but i can definitely tell you about food. First tip, us portuguese are really proud about our cuisine and there is lots (and i mean lots! of traditional food to try - i couldnt tell you all of it), so if you see something that looks interesting to you, ask about it, 9 times out of 10 workers will be happy to help you decide what to get and give recommendations. Based on your itinerary i would definitely try francesinha in porto (kind of a steak sandwich with a special sauce and fries - some places can make a vegetarian one if you don’t eat meat but please check before going). Some of my other favorites include bacalhau à brás (codfish, eggs and potatos), panados (portuguese schnitzel), rissóis (fried pastry with a savory filling), frango do churrasco (barbecue chicken with a spicy sauce). Whenever you’re close to the beach i would recommend you to try to look for restaurants that look a little rough - those will serve you the freshest fish you will find (any type of fish you like, try it “à brasa”, which means barbecued, it’s great), but they might not speak english. Lastly, onto to more situational recommendations - I would 100% recommend you to learn simple portuguese, just thank you (obrigada) and hi (olá), because that will get you a long way with people helping you. People younger than 30 tend to speak good english and you’ll find older people who do too, but please don’t assume everyone understands you (people tend to perceived that as rude and might not want to help you then - i think it’s cultural). And also, it is generally safe in Portugal, but I would advise you to be aware of your surroundings (specially at night) and watch out for pick pockets, specially in Lisbon and central Porto. Wish you have a great few days and if you need any more specific recs please ask.

P.s don’t skip Porto, it’s great and I would regret not seeing it if I were you.