SASTRA (Deemed to be University)

Actually, in Sastra University, they won't consider B.Arch marks in admission process. Basically, for getting into Sastra University, there are two processes.
Stream 1: which is JEE + inter marks
Stream 2: only inter marks.
For your son, considering the given data, getting seat is difficult. There is no donation seats. But, some seats are available in NRI quota and NRI sponsored quota.

Hi, you have a fair chance of getting into SASTRA. Do download the application form from the website and apply.
All the best!

Yes, it is possible in Sastra University to get admissions through Lateral Entry. For better information about courses you can go through this link https://www.shiksha.com/b-tech/course/b-tech-in-computer-science-and-engineering-lateral-entry-srinivasa-ramanujan-center-shanmugha-arts-science-technology-and-research-academy-thanjavur-300297

Yes, you can get admission in Sastra, but I'm not sure whether you can get your desired course.

Yes, you can apply for it. There are high chances of you getting a seat if you apply.

Hello Dhanush, approximately 9 lakh students appeared in JEE Mains exam in January. Another 1 lakh fresh candidates are likely to apply for exam in April. You have 80 percentile. Hence 20% of 10 lakh or 2 lakh students are ahead of you. Hence, you should be within mark of 224000 announced in newspapers.
Best wishes to you.

Yeah, he had chances to get seat in bioinformatics or biotech in sliding can change to mechanical or EEE.

Yes, you can expect CSE there. Till 500, there's chance to get CSE.

You can get CSE there as you are a localite.

Check here rank and college cutoff and get the opening and closing rank for the expected college and your son eligibility.
Link: https://www.shiksha.com/b-tech/resources/jee-main-rank-predictor