The importing part was already explained and regarding on exporting, you can still do it but it's not gonna be on blockchain.info as it's no longer supported there.
a. Run this locally:
https://iancoleman.io/bip39.
b. At the BIP39 Mnemonic textbox, type in your seed.
c. Make sure you're on BIP44 tab and go to Derived Addresses at the bottom where as the name implies, you'll see your addresses and their corresponding private/public key
- To view your change addresses change "0" to "1" in the External / Internal textbox
- To toogle accounts, just change the value in the "Account" field (0= default account, 1= 2nd acc....so on)