Fergusson College

Yes, you could secure admission in Fergusson College through management quota. There is a 15% reservation for under graduates in the first year. However, many people get through even with an average percentage. There are 3-4 cutoff lists, and you may not have to wait for the 3rd or 4th cut-off list.

If admission date is over then you can't do much now for this college. Try other colleges where admission is still going on, it would be better not to waste one year for a specific college. It is the subject that matters more than a college if you are keen on studying microbiology.

Yes, you can provided you are there on the merit list.

Yes, you can get admission in all the three colleges.

Hi Akshay,
I actually don't know about the college you mentioned, whether it's good for B.Sc in physics or not. But what I know is that St. Xavier's College, Kolkata is really very good for that particular course. Presently, SXCKOL is the best college rather an institute under UGC all over India with a score of 3.77 out of 4 and I am not saying this, it's according to the NAAC.
All the best.