UPCAT

Hello Aditya,
As per your rank, your chances are very slim for getting any government college. However, check here for more insights:
https://www.shiksha.com/b-tech/resources/upsee-college-predictor

Yes, you get it kindly visit the link provided to get your college detail by your score rank and category.
https://www.shiksha.com/b-tech/resources/upsee-college-predictor

Yes, you can get Galgotias University. Your rank is good and percentage is also good. Visit there website for more details. Also, participate in UPSEE Admission Rounds.
Good luck.

No, UPSEE marks are valid for just one year. That is, only for the year of examination. UPSEE do not allow previous years ranks or score .You have to use this year's marks.

You know 24000 rank in OBC category is a very poor rank. You may get admission in bottom private colleges. I will suggest you to take direct admissions in any private institutions of UPSEE.

Yes, you can register in open category. See, at the time of counselling talk to the administration department. They will provide you proper guide lines for this.

You have many colleges like G L Bajaj Institute Of Technology And Management, Galgotia Institute Of Technology, JSS Institute of Technology, Ajay Kumar Garg Engineering College I.T.S Engineering College and many others.

Yes, you can get admission in UIET, Punjab University. It is the best government college that offer you good placements. You may also get PEC College in Chandigarh, which is better than UIET with better placements.

Kindly visit the link mentioned below:
http://www.uptunews.in/2014/04/upsee-uptu-2014-top-engineering-colleges.html?m=1
perfect site to Know what's is best for you.
All the best