I want to invest in bonds in the secondary market through my trading a/c. How will the bond issuer pay me the periodic coupon interest? Will it get credited in my trading a/c?

Coupon Interest will directly credit to clients bank account and not trading account.

How will the bond issuer (say NTPC) pay the interest in my bank a/c if I buy the bond in the secondary market through Zerodha? NTPC won’t have my bank a/c details since I didn’t buy directly from them

Bank account detailes are present with depositaries and when any carporate action takes place company registrars will take the details from them to pass the benefits.

What are the debt and bond market trading timing in India? Is it traded primarily on BSE and NSE?