ILS Law College

The cutoff for BA LLB (outside open/general category) for the last academic year, i.e. 2017-18 was 107.

The cutoff for BA LLB (outside open/general category) for the last academic year, i.e. 2017-18 was 107.
Given this, you seem to have a chance, decent one.
Best of luck.

See Page 7 of the following link https://ilslaw.edu/wp-content/uploads/2018/07/Notice-of-I-BA-LL.B-1.pdf
The annual fees for I BA LL.B for reserved category NT is Rs. 36,790 as per the published data.

Since the query is specific to "Post Graduate Diploma in Alternate Dispute Resolution Mechanism", I believe graduation is the required qualification.
As regards the marks requirement and cut-off (if any), I do not have any data. You could call up college and inquire.

Admissions in ILS are through MHT CET. While the 12th marks are considered, they are only used as a tie-breaker in case the MHT CET score of the candidates is the same.
CLAT score is not considered for admission.

With regards to the 1st question, one can always call ILS and understand or just pay a visit to ILS.
Diploma is a residential course.
For the 2nd question, no education goes waste, is all that I can say. Whether it is useful or not is a personal prerogative, given the career choices one has.

The website (https://ilslaw.edu/) is the best place is the best to get most information. As regards to admission in ILS, it is now through MHTCET for LL.B and B.A. LL.B., while admission for LL.M. is managed by ILS under the guidelines of Savitribai Phule Pune University. The MHTCET form is available online on their website.

Being a B.A.LL.B. candidate, I cannot answer with confidence about LL.M., and I do not want to misguide.
As regards to the notification, a merit list has been published on the ILS website at:
https://ilslaw.edu/announcement/first-merit-list-for-llm-first-year-2018-19/

When one asks which institute is better, it is tricky to answer. I personally do not have enough knowledge of BHU, but I guess the law programme has recently been introduced, probably in 2013-14.
Being from ILS, I can boast of the tradition of 100 years, the most amazing library facility, and a campus in the lap of nature. So, I would be biased in its favour.
You can read the reviews of ILSAT on the following link and make your own opinion:
https://www.shiksha.com/college/ils-law-college-law-college-road-Pune-2499/reviews#206995

I cannot predict the cutoff and give any wrong expectation. But I can give you the cutoff for the categories you asked for the last academic year, i.e. 2017-18.
For BA LL.B (outside open/general category), the cutoff was 107.