Managing with the languages
Barcelona is the capital of Catalonia. Although everyone will speak Spanish, you have to get some familiarity with Catalan to live here - at least to be able to read official notices at least. For instance official notices are in Catalan, as is all the information you might receive from school.
And if you do have children at school, their homework will be in Catalan. The first catalan reading comprehension exercises for our eldest child took 4-5 hours of painstaking word-by-word translation so we could help with the comprehension questions - including writing the answers in Catalan.
Although Catalan is the principle language of the city, it is the first language of only around 50-60% of people living in the Barcelona with the remaining people speaking Spanish. There are large numbers of people from South America and other parts of Spain here who only speak Spanish and this means most schools have to cope with non-Catalan speakers. Outside BCN city Catalan predominates.
According to newspapers only around 25% of people in Catalonia speak a foreign language so you will find that talking to 'natives' outside the tourist areas many will not speak and probably won't understand English and you shouldn't expect it. But around the tourist areas in the city English will be spoken and there is a large ex-pat community from UK, Ireland, Germany and the US and there is therefore a lot of English around the city, not just from tourists, but also from residents. Nevertheless even in bars and shops, English is not heavily spoken, and may not be understood.
To help with my verbs and tenses I have a little verb drill for Spanish, and a separate one for Catalan.