1) Does every noun in Arabic have a singular, dual, and plural?
No. Certain words, like the name Allah, only exists in a singular form. Some plurals (as you will learn later) do not have a singular (e.g. إبل meaning camels). Other words are commonly used in the plural form in the Qur’an even though they have a singular word, like the word dhulumāt (darkness).
2) If the accusative and genitive patterns for the sound plurals repeat, how can I tell the difference?
Other context clues can be used to determine if the case is accusative or genitive, such as the presence of genitive particles or the iḍāfah structure which we will learn later. Remember that Arabic grammar is very logical and does not typically leave the reader is very ambiguous positions.