Colleges in Chennai

Yes, you should wait for the result. By the way, you got decent rank in VIT. You will get CSE with this rank in VIT University.

Prefer Anna University, as it has good reputation and name for several courses. Second option, you can keep for PSG. Anna University is top in Tamil Nadu.

Yes, it has got good reputation in graduation with good infrastructure. You can prefer Guru Nanak for your BBA. But, you can go for MBA for bright future.

The better one is VIT-Vellore because it is widely preferred by the students for B.Tech and CSE. SRM is also good but if you get VIT go for it.
Both are good but the fee structure is a little high as they are private universities.
Salary packages depend on the candidate's skills and also the companies

Yes, SRM offers B.Tech in mechatronics.

Yes, it is a good one, but the fee structure could be high as it is a private university.
Placements are good. SRM University main campus is mostly preferred.
Select a good course as many core companies will be coming.
All the best.

Right now,
You are not late.
You can join easily.
If you think about lateral entry, then they charged more donation.

Yes, JIIT 128 is better than SRM Modinagar for CSE branch, if you talk about only placements.
Though JIIT 128 is still a developing college in terms of infrastructure and facilities, I would still consider it better than SRM.
Reasons to choose JIIT 128:
Comes under the parent JIIT 62 which is pretty go

Eligibility requirements for part-time MBA programs are quite similar to the requirements seen in full time MBA programs. Just that these programs are designed for working professionals with at least two years of work experience.
Candidates will need a Bachelor's degree or equivalent in any disciplin

Your class 12th marks is good, but this is not enough, you have to qualifying their entrance exam to get the admission in this college.