Which “it” are you referring to? If by “it” you meant that “need” was accepted in a translation for this sentence, then that should be reported as an error.
They accept both "want" and "need" in these types of sentences, just as they accept both for teastaigh. Which, I agree, is absolutely horrible.
It came from from your discussion of Ní raibh uaidh ach sin being translated as "That was all he needed" or something similar. In my dialect of English, however, that would still translate as "want" (He didn't want but that)
I also too was told that "you" was wrong and the correct answer was ye. All the rest of the sentence was correct.
That makes sense if you think of "ye" as the antiquated plural of "you" (as in "O Come All Ye Faithful". I tend to say "you all" if I need to emphasize a plural "you", but it's awkward.
Which word represents the verb 'wants' here please? I just don't get it...
Just as Irish doesn't have a verb for "have", using tá X ag Y to say "Y has X", and an bhfuil bróga glasa agaibh? means "do you have green shoes?", you can use Tá X ó Y to say "Y wants X", and an bhfuil bróga glasa uaibh? means "do you want green shoes?".