Colleges in Ahmedabad

First, you will have to take CMAT exam and in CMAT also you will have to score around 95 percentile. Last year's cut-off of CMAT for BK was 94.55%ile. After the declaration of CMAT result, the registration for participating in the admission process for the colleges under ACPC. Admission will be done through ACPC only on the merit bases.
All the best.

As far as Great Lakes is concerned, you have slightly dim chances.
All the best.

It is really difficult for engineers to enter IIM-A with a low percentile. You should ideally take the CAT exam next year and aim for a percentile greater than 99.5.
Also, there is no work experience criteria for getting admission into IIM-A, however, you may get benefits from your experience to enter into other IIMs.

There is no specific eligibility criteria for class 10th and 12th percentage, there are just ratings associated to these scores. So, it is recommended that you aim for a high percentile to make it to a good IIM so that your ranking based on a weighted average score is good.
I cannot pinpoint to a specific score because it is all relative, but you should aim for a percentile >99.

The admission criteria has several considerations such as CAT percentile, prior academics, and diversity in educational background. Although one cannot guarantee anything, having done well in any of these does increase your chances of making it to the final selection.

Yes, such loan schemes are offered by several banks such as SBI and CBI.

The current fee amount is Rs. 21 lakhs for two years, which includes tuition and accommodation (excluding food expenses).

The selection of the candidates for admission to the 2018-20 batch of the PGP at IIM-A is a two-step process.
In the first step, candidates are short-listed for Academic Writing Test (AWT) and Personal Interview (PI) from among the candidates who have a valid CAT/GMAT score, who have applied to the programme and who satisfy the eligibility criteria for the programme.
For the eligibility criteria, you can visit the website.

You are eligible as you clear the minimum eligibility criteria and you have good chances according to your scores. The shortlisting criteria for interviews of Iims is based on CAT score, 10th, 12th and graduation scores and work experience. However, the weightage given to this parameter is different for all Iims and also depend on category and academic diversity. You can use the call predictor to check your chances:
https://www.shiksha.com/mba/resources/iim-call-predictor.