Would "Eu pagarei para o seu almoço hoje." also be correct? That is, is use of the preposition "para" redundant?
I want to ask the same question. Let's hope that someone will answer, sooner or later.
When is it appropriate to put the article in front of the possessive pronoun, and when is it not? I feel like I was taught that the article almost always tags along, but in Duo Lingo, if I put it in, sometimes it is wrong and sometimes it is correct. What is the rule for that?
I live in Portugal, not Brazil, and here the rule is that the possesive NEVER replaces the article. Quite unlike English, if the sentence would require an article without the possesive then the article HAS to stay (o meu livro, o teu amigo, a sua amiga, etc). I believe that in Brazil it is more flexible.
As for Brazil: most of the time, the article is there to specify a certain noun. And it is a rule that all nouns must be specified (unless it's one of those tricky exceptions).
The thing is, the possessive is also a specifier. So it is sort of redundant to specify a noun twice, unless you really want/need to put emphasis on that.
The official rule is that it is optional. And then some people are used to using them, some aren't. I would say that most of the time, specially when speaking (when everything is simplified), we simply avoid it since it's not necessary C:
What is more common to say: 'Eu vou pagar o seu almoço hoje.' or 'Eu pagarei o seu almoço hoje.' and what is the difference?
Grammar-wise there's no difference: both are proper formal ways to use the simple future.
Now, in conversation/daily use... Years ago, vou pagar was considered informal, colloquial speech. Then it was used so much that it was "promoted" to be just as formal as pagarei - and this is not recent, it's been like that for decades.
Because of that, still to this day, some people still argue that vou pagar is informal and you shouldn't use it in a situation that demands some respect or formality. But that's a school of thought, it's not true to the reality - at least not here where I live. I'm sure the region plays its part too, but I wouldn't worry too much about it - both forms are used/known everywhere and I would say vou pagar is more common C:
Obrigada, Vinidcali. And in a situation when two people are having lunch in a restaurant and it's time for the bill it would be also natural to say: 'Eu pago hoje.' Right? It all depends on the context. Thank you so much.