Opening a bank account as a non-resident is a fairly straightforward procedure. All you will need is your passport or national identity card, and proof of address. You will be given either a debit card or, in some cases, a "llibretta", which is a small booklet that you insert in the cash point for withdrawing money. The only advantage is that all transactions are printed out so you can see exactly what the incoming and outgoings are.
A credit card will only be given to those who have a work contract. Even then they usually require that you wait a couple of months before applying for the credit card so they can check that the account is being run correctly.
English speaking financial consultants and agencies specialising in personal and business money matters can be found here Barcelona. With all financial decisions, it is always a good idea to research and consider the various available options very carefully.