Wallet is view-only and sends are only possible by using offline transaction signing. Unless key images are imported, the balance reflects only incoming but not outgoing transactions.
Verify that funds were paid to an address by supplying the transaction ID, the recipient address, the message used for signing and the signature. For the case with Spend Proof, you don't need to specify the recipient address.
Use this feature if a transaction is missing in your wallet history. This will expose the transaction ID to the remote node, which can harm your privacy.