Exam

No. GRE entrance is meant for Masters applicants. In your case you will have to take german entrance exam known as feststellungsprufung after completing Studienkellog in Germany

What is your category?

Getting a seat in these colleges is very easy. You just need to have 60% above marks in 12th and since you have an average JEE score, you can directly contact them for the admission in their office. They won't offer you CSE or IT. But you can go for other branches.

There are certain criterias to get admission in a good college through UPTU(AKTU). Firstly you should have a minimum of 60-70% in PCM and also you should have given UPSEE exam with good rank.

There are tons of engineering colleges in Ghaziabad and Noida. Among them, the best ones are JSS-Noida, KIET-Ghaziabad, A. K. Garg-Ghaziabad, Galgotias-Greater Noida, G. L.Bajaj-Greater Noida, ABES-Ghaziabad, etc.

Hello Ranvijay,
You may refer the link below that gives the college predictor for UPSEE examination which may suggest some colleges that you can get with your score and rank :
https://www.shiksha.com/b-tech/resources/upsee-college-predictor

Your sister should surely try for a government college. It depends upon the ranks and availability of seats in that particular college. You never know she may get one of the best Govt. Colleges. All the best

It cannot be determined if you will get admission in BBD or not just depending on your ranks. Firstly, you need to apply for BBD through UPSEE counseling then only after the results of the counseling you will be able to know about your admission status.

No, you have to go through the paper of COMEDK for getting admission in the top colleges in Bangalore. You don't need JEE Mains for the same. Bangalore is the best option for doing CSE through colleges like RVCE, MSRIT, etc.