You can buy the tickets at the castle, but, to avoid a queue ( even if small) and make most of my time, I would recommend buying it beforehand. Prague city pass is a great option( I would definitely recommend buying it from a tourist information centre. They would tell you things that you would not have known and offers that would make the most of your visit enjoyable. But, please bit the audio guide beforehand.. they sell out too fast and you would want one to have a complete experience of the castle.

The initial entrance in to Prague Castle is free. You can pay on the day if you wish to explore inside e.g the Cathedral.

Yes it is open you just have to wait in line, Usually the lines are so long, I did not wait because it was too long

Sim, tem um restaurante no local mas não muito variado

We only went into the courtyard. Were told it wasn’t open but certain times of the year since it is a working seat of govt.

Anche io avevo gli stessi dubbi tuoi. Ho fatto i biglietti direttamente al castello. Ti danno l'audioguida in italiano, a pagamento e con cauzione di mille corone. Nel biglietto puoi includere una serie di cose da vedere e paghi in base a quelli che vedi. Ne vale la pena sicuramente è con l'audio guida non fai le corse come se avessi la guida

We didn’t buy tickets. Access to view the changing of the guard, to the main entrance of St Vitus Cathedral and the castle grounds is free. You can buy tickets for the remainder of the Cathedral and one of the streets. But not necessary.

I would not think so at this time of the year ... in summer you may have to We used the the premiant tour company so it was all paid for. The police will search your bags on entry and this can hold things up on entry.

Salve assolutamente Siiiiiiiii...!