When I got to blockchain.info and log in and it asks for my Wallet ID and password, is the Wallet ID my private key?
Does having this saved in the browser create a serious vulnerability to it being hacked?
When I sign into blockchain and select request and it comes up with the Copy and Share address, this is what is meant by the Public Key, right?
No, wallet ID is
NOT your private key. Wallet ID is like your "username" (as in Twitter and Instagram) in Blockchain.info Wallet ID has nothing to do with the Bitcoin network, it is only meant to be use in Blockchain.info service. But still, you shouldn't publicly show your Wallet ID for security reason.
I think it's safe to save your wallet ID in your browser as long as you
keep your computer secure.
Yes, the address that written as "Copy and Share address" in blockchain.info is your Bitcoin public key (i.e. Bitcoin address). Unlike Wallet ID, Bitcoin address can be used in all Bitcoin-related service, not just blockchain.info