Practice with Nominative and Accusative

.يفعل الاستاذُ في مدرستاَ

( الاستاذ" البروفيسور" يعمل في مدرستنا ،يعمل الأستاذ" البروفيسور" في مدرستنا)
The professor works in a school.
اكلتا اختانٌ اثنتان الفلافلَ.

( أكلت الأختان الفلافل، الأختان أكلتا الفلافل)
Two sisters ate the falafel.
ذهب الى المسجدَ الرجلُ.

( ذهب الرجل للمسجد، ذهب الرجل إلى المسجد)
The man went to the mosque.
يدرس ابن عمي ادلرة الاعمل. ممتاز  
My cousin studies business administration.

I am trying to focus on the pronunciation of nouns and objects in these sentences.
I have a couple questions:
1) In a sentence where there is an adjective after a noun, like "Two sisters ate the falafel", do you put a ٌ on اختان?   No we don't add, just the noun and the adjective.

In Arabic, for definite nouns we use ال, the same as in English; for non definite nouns we don't add any thing before the noun but then we should add an adjective after the noun to be understandable.

e.g: 

ذهبت إلى المدرسة ( definite)

ذهبت الى مدرسة ( non definite) we should add an adjective at the end.

2) Do you include a ٌ on a subject if there is a pronoun, like in "My cousin studies business administration"? 

No.

Thanks so much! I really appreciate the help.