Can we use "Quem acreditará naquilo?" Why is irá used in this example?
Right too. Irá is the verb ir (to go) conjugated to express future actions (as well as using "going to" in English).
Just to make sure I understand, "vai acreditar," irá acreditar","and "acreditará" all mean the same thing? And in normal conversations, "vai aceditar" is the most common? And I think "irá creditar" is the most formal?
Yes, they are all the same! =) for me, the most formal is "acreditará". "irá acreditar" is considered grammatically incorrect.
Is there an additional significance to using the future tense while already using "ir + inf"? In other words, does this differ from "Quem vai acreditar naquilo?"
I am right now in Portugal and it seems that people here say "Eu nao acredito", but they don't say "acredito" in the same way. I'm not sure if it is a joke, but it usually sounds "akerrdito", "Eu nao akerrdito!"
I think even in Brazil some pronounce it like that! I read a comic book from Brazil where the character really says "aquerdito".
Yo what is with the third person, plural conjugation of "acreditar" in the future tense? The top of the "a" looks funky and I can't even find that symbols anywhere else or an alt-code to form it. What is it?
¿?¿ If you are doing this from the web, you have several buttons available under the text box when you are asked a question. One of them will be the symbol you are looking for (probably ~ ) If you are doing this from the phone, just hold the "a" key to see the different options, one of them will be what you want...