Learn Farsi: چقدر کره روی میز است؟ - How much butter is on the table?

cheghadr means "how much" and is used to ask about quantities of uncountable things. Just like in English, you place it directly before the noun you are asking about to make cheghadr kare (how much butter).

Could I use chand instead of cheghadr here?

No, because kare (butter) is an uncountable noun. chand means "how many" and is only used for things you can count, like chairs or books. Since you are asking about an amount of butter, you must use cheghadr.

Why isn't there a visible connector between rooy (on) and miz (table)?

Prepositions like rooy need a spoken linking sound called the Ezafe to connect them to the next word. It is pronounced rooy-e miz (on the table). This short "e" or "ye" sound is rarely written in the Farsi script, but you always have to say it.

Why is the verb ast (is) at the end of the question?

Unlike English, Farsi doesn't change its word order for questions. The verb almost always stays at the very end of the sentence. The question word cheghadr simply sits where the actual amount would be in a statement.