2A an 3 B difference

1. You can make payment through DRC-03 by choosing Voluntary option through credit ledger, but before filing of GSTR-9.
Kindly note- you will have to pay Interest @ 24% p.a. using "Cash Ledger"

2. The time limit for availment of ITC for F.y. 2017-18 and even for 2018-19 has been passed, so now you can not avail ITC if it is showing into GSTR-2A

1. No Not required but must have the Original copy of Tax Invoice .
2. No you cannot claim in GSTR 9 as it's not going added to your ECL