when you made plans about future you can say ''i am (verb)ing ....'' (it means it is probably going to happen, i made a plan) although the grammer looks like present the sentence still indicates future. (you better use time adverbs in these kind of sentences)

are

Which city of India is called pink city? (I think the answer is Jaipur)

quadruple

It means they gave him nothing, they didn't give him food and clothes. This is 'neither .. nor ..' form and has negative meaning. They didn't give him either food or clothes. (this sentence has exactly same meaning with your sentence)

i am going to go my sisters wedding" you cant go to a marriage, wedding is something that people wants to celebrate their marriage.

in indicates inside of school, for example i am in the school now. at indicates that place, for example i am working as a teacher at a school

This sentence is correct. You can use "The system which i was working on is suddenly stopped" if you want.

grass

"I made a cake yesterday" is correct, your verb have to be past form because you did it yesterday