Use Preapproved Kotak Debit card EMI for Credit Card

Deal Newbie

My CIBIL is 773.

I have 811 account with AMB>60k with good number of transactions too.
I got this Kotak Aqua/811 Credit Card around 13 months ago after getting rejected twice for 1. LOW CIBIL 2. Negative area/Unsuccessful physician Verification.

Now, the bank has offered me Pre approved Debit Card EMI/Consumer Finance with limit of 2L.

So, I am planning to apply for a unsecured card now basis this offer.
But the Kotak system doesn’t allow for an additional card along with a FD based card.(Tried and experienced this twice).
So the executives are asking me to close this FD card and then apply after some time again.
But I am reluctant to close that card as it is the oldest active account in my CIBIL with 0 late payments and 0 fees.

So guys please advise

1. What are the chances of approval of application this time considering Debit Card EMI offer and which card to apply for Online Shopping and low fees?
2. Does closing the oldest active account makes an impact due to dip in age of account?(The next oldest account is 6 months younger which I also plan to close for high fees and the oldest closed account is 2 years old).