We would like to give some advice in order to book your flight.
There are three airports in Catalonia (the autonomous region Barcelona is in), that are frequently referred as “Barcelona airports” by some airlines. The truth is, there is only one airport in Barcelona, called El Prat. The other two are in Girona and Reus (Tarragona). You have to keep in mind the extra time and money arriving at these two last airports will imply.
There are many means of public transport from this airport: the regular bus (although we don’t advice you to take it, it takes long time and you could get lost); the train (cheap and safe, it takes you to Passeig de Gracia station, quite near the area of Semiofest venue) or the Aerobus (a bus that goes directly to Plaça de Catalunya, right in the center of the city). It charges 5,75 euros per single ticket and 9,95 per return ticket (valid RETURN up to 9 days after purchasing).
If you choose to take the train, the T-10 (10 integrated non-personal trips) card is valid, and if you’re planning to take some public transport, it´s better to buy this (9,80 euros) than a single ticket (2 euros).
And of course, there are taxis: a trip to the city centre will be around 30/35 euros.
The fares for this bus are 16 euros (single ticket) and 25 euros (return ticket).
If you are coming by train, the international station in Barcelona is called Sants. Here you have the information of the Spanish national train company, RENFE (although we strongly recommend to check your local websites, as this one is really messy to book international tickets). This web (that has international versions linked to it) is better: http://eurostar.tgv-europe.es/es/
And if you have any doubts or queries, please do write to us (firstname.lastname@example.org).
Regarding visas, please check the official information here.