"I eat bread."
Translation:Eu como pão.
The technique I use to pronounce Portuguese words or parts of words is to select an Englsh word with a similar sound and modify the English sound as necessary. For "pão" I se!ect "song", substitute a " p" for the "s" and go light on the "n" and the "g". The feedback I get from native speakers is a passing grade. I believe the technique should work for any combination of languages. I am a native English speaker.
Because you have to conjugate the verb for the person you are referring to. The same reason why I'm English you say "I eat" and "He eats". If in doubt just search for Portuguese verb conjugations and memorise the present to start off with.