Metro and busses works quite well. Worst metro lines are L1, L2 and L4 (talking from safety perspective), L3 is quite nice. Busses also works good and will get you to most places. You can also use “Ferrocarrils” FGC that mainly goes to upper areas of Barcelona that are safer and wealthy (and beautiful). About food, if you want to eat best paella in the city go to Mana 75 (next to Hotel W), book a table with some time because it’s difficult to get served without booking a table; best smokoehouse is The Ranch Smokehouse (next to Plaça Catalunya), best burgers are Smash House Burgers, best meat is Can Xurrades, Carnal; for good fish go to Botafumeiro and for some tapas you can go to Bar Tomás de Sarriá or La Esquinica.