in a couple of days I will have a business trip to Lisbon, which was requested at very short notice (so I have really little time to organise myself).
I have been quickly browsing through Metro Lisboa website and I have seen that there is a very convenient connection via Metro from the airport to Oriente, where my hoteel is located.
I am not sure, though, whether single "paper" tickets are available or whether the only way to use the Metro (even with a single fare ticket) is through a Viva Viagem card, as the website seems to suggest ...
Is Viva Viagem card mandatory for travelling in the Metro network also on single fare tickets?
Also, I see that a single fare ticket is valid for an hour on Metro and Carris; is interchange allowed? E.g.: if I want to go to Bairro Alto for dinner, can I take Red line in Oriente and switch onto green line until Chiado with just one ticket? And in case I am still within the hour, can I hop onto Elevador de Santa Justa to Largo do Carmo (operated by Carris) with the same ticket?
Thanks in advance and sorry if this has been asked before (I would usually "do my homework" and research more deeply myself, if I hadn't such a short preadvice!)