I would say that English is awkward, with its inversions and the need to use an auxiliary verb to make negations. ;) Every language is awkward, is you compare it word by word to another and expect it to be the same. :)
You should think at "Quanto" as "How much" instead of "how" alone, I think. In this case "How" express quantity, but needs big next to it to make understand that it's speaking about quantity, dimension, whatever.
Italian's "Quanto" already imply that we are speaking of a volume/amount and not about a procedure.
"How" alone is "Come".
I have looked for some stuff on the net but cannot find anything useful.
I think this is the structure to use with "quanto" + essere + adjective.
Quanto è grande il tuo appartamento? How big is your flat?
Quanto è alto tuo padre? How tall is your father?
Quanti anni ha tua madre? How old is your mother - because here "anni" is a noun, not an adjective! we don't say "Quanto è vecchia tua madre?" it would sound SOOOOOO rude!
In English, the word order changes completely when you ask a question, but this is not the case in Italian at all. There are no auxiliaries such as do or does to mark a phrase as interrogative. In fact, you could change this question mark into a period and it would still be grammatically correct, with a meaning similar to "My, how big your cat is." Here are other examples:
- Do you have a car? Hai una macchina?
- You have a car. Hai una macchina.
- Abbiamo un piatto? Do we have a plate?
- Abbiamo un piatto. We have a plate.
Interrogative pronouns, adverbs and adjectives (such as dove/where, chi/who) generally go at the beginning, but on special occasions these can be moved around for the sake of emphasis.
- Chi è lui? Who is he?
- Lui chi è? Who is he?
- Dove sono i ragazzi? Where are the boys?
- I ragazzi dove sono? Where are the boys?
Big is not equal to Fat. Big is all about the size(how much space it takes up), it doesn't matter if that space is made of fat. The cat could just be bigger in size.
"Your cat is too big" ... "It's actually a little tiger"
"Your cat is too fat" ... "Yeah you're right, I should put it on a diet"