Hello
My answer folling.
1) 2009
2) satoshi
3) store value or currency
4) Ethereum ETH
5) public key can be public shown to any one as address to receive fund. private key is must keep in private to send fund,sign message etc.
6) any one who own 51% or more mining power, can make this attack on bitcoin for double spending for his own benefits.
7) double-spending is term used to define spending same value multiple time.

04 march 2020 (i googled this i was not sure about date but i remember year 2020)
9 ) e₹
Regards,