IIM

Chances of getting calls from older IIMs will be low, you can get calls from newer IIMs (Kashipur, Udaipur, Raipur, Rohtak, Amritsar, Sambalpur, Bodhgaya, Trichy, Jammu). A good performance in WAT-PI will enhance your chances of converting the calls.

It depends on your CAT score. If your percentile is above 99, however, you need to be in the graduation final year without any backlog in order to be eligible for appearing in CAT.

Yes, you get weight.
The application form does ask for work experience details but it is not mandatory. However, during the final selection of candidates, work experience is given some weightage by the Iims. The exact weightage given to work experience is never revealed by the Iims but it varies from IIM to IIM.

What is your sectional cut off?
If you are from general category and if you clear the sectional cut-off which is 80+, the new IIMs and IIMs other than A, B, C can give you a call.

If you want to opt MBA as your career then you should go for BBA field as it will cover your half basics of MBA.

Yes, AMIE degree is totally valid for admission into IIM's.

A good score in CAT may enhance your chances of getting a call from IIMs. Your academic is pretty decent except 12th percentage. You need to score at least 97-98 percentile, to get calls from newer IIMS. For top IIMs (Bengaluru, Indore, Ahmedabad, Calcutta, Lucknow) will be a tough chance.

Try for FMS, NITIE, SIMSREE, JBIMS, IITs, NITs and look for baby IIMs too.