IIM

You will get a call from every good college except IIM-A and B with this score. Your B.Tech score might be the reason for this.

They actually call regular students, at the time of application you shouldn't have any back otherwise no one will call you.

The earlier you start your preparations, the better and more continuous your academics will be.

Yes, you can take an education loan after completing your MBA from IIMs. All the reputed banks will be ready to give you education loan very easily for pursuing your further Masters.

The top 5 IIMs require 60% in class 10th, 12th and UG. Since, your past academic records are low, then you need to score above 99% to get a call from top IIM's.

You have chances to get admission in new IIMs (Sambalpur, Bodhgaya, Sirmaur and Srinagar). You have chances to get calls from IIM-Rohtak, IIM-Udaipur, IIM-Kashipur and IIM-Trichy.

IIMs don't offer a specialization. They offer a PGDM course (not an MBA) without any specific specialization. However, you have an option to select elective courses in the second year as per your interest. Even though you won't get a degree in IT in that case, but you'll learn about it and will have better chances of getting into an it company post MBA/PGDM.

Hi,
I am afraid you can't. IIMs give a good weightage to X and XII marks for admissions.
You can also visit the following link to find out the IIMs you are actually eligible to and your tentative chances of getting a call:
https://www.shiksha.com/mba/resources/iim-call-predictor

No, work experience is not compulsory. However, a couple of IIMs give extra points to students with work ex.
Regarding preparations, the earlier you start the better it is since there are a lot of things that come with practice. You should at least give 8-12 months for a proper preparation and join a test series for sure. TIME coaching has a good test series. It starts around 4-5 months before the CAT date.

Since you graduation grades are little low, I guess you might not get a call from IIM-C and IIM-B. But, apart from that you can expect a call from most of the old IIMs and new IIMs.