Just to make sure I understand perfectly. Would I use the imperative as follows:
(Tu, ) abrE a porta por favor ! = (You, ) open the door please !
(Você, ) abrA a porta por favor ! = (You, ) open the door please !
Thank you both, Gents. I really appreciate your invaluable help to me. I still need to figure out the Portuguese imperatives (it baffles me to see 1st person plural and 3rd person singular and plural on the conjuga-me.net site). English imperative is rather simple and bland in my mind, or little more than a name for an order to the implicit 2nd person (sing. or pl.) or so stern a request mounting to an order. Personally I feel adding the pronoun You to an imperative sentence can be more personal and forceful (or rude). The "shall" statement in English would be a different category than what's discussed here.
From what I could gather, Portuguese imperatives might not differ much from that in English - in that the future tense could be just as forceful? Are there any quick guides on do's and don'ts in using them? How does the imperative for ele/a and eles/as work - how would they know for a start that an order is issued for them to obey? Sorry for these unintelligent queries! I will take the time to read up on them. Thanks again.
Actually, the imperative is related more to you (tú, você), nós (we) and eles/elas(they). Then it is easy to distinguish. You can include yourself (leiamos o livro - let's read the book) and to a group of people: leiam o livro (you all, read the book). the ending of the verb is the clue to identify, so there is no need to add the pronoun. I know it might be hard since there are some which are irregular and two ways for "you" (tu and você) but I don't know any guides for this...