When introducing myself in japanese should i say my name as it is said in Portuguese? I mean should i use japanese like Migeru (if it is how you say Miguel) or Santos (last name) or say it as it is said in the original language ?

How do you say "you're welcome" in reply to "thank you" in japanese?

How do you say, "I am portuguese" and "I speak Portuguese" and also japanese for Portugal, thank you.