XLRI Xavier School of Management

XLRI is applied separately. XAT decides the cutoff after which GD/PI is conducted and admissions start with counseling rounds.
You can check the below mentioned link:
https://www.shiksha.com/mba/course/postgraduate-diploma-business-management-xlri-xavier-school-management/113077

There is no reservation in XLRI. There are some private organizations which give scholarships to students based on both means and merit

XLRI is one of the top 10 management institutes in the country. IIFT is a very good institute as it is ranked among the top 20 management colleges. The graduation marks won't be an obstacle, if you have a very good entrance exam score or a very good profile. However, top b-schools require minimum first class in graduation.

Your graduation score won't fetch you admissions in XLRI. However it would be helpful to maintain a good, academically sound profile. Which would help you in placements.
For XAT cutoffs change every year, last year it was around 94 percentile for HRM and 96 percentile for BM.

Most probably third week of June.

You must have completed graduation or will complete by June, 2017
For admissions you need to give XAT-2017 exam. On passing offs the cutoffs you need to appear for GD-PI process. After which final results are declared.