The AbiCoder is a collection of Coders which can be used to encode and decode the binary data formats used to interoperate between the EVM and higher level libraries.
An EIP-2930 transaction allows an optional AccessList which causes a transaction to warm (i.e. pre-cache) another addresses state and the specified storage keys.
Often only the hashes of the transactions included in a block are needed, so by default a block only contains this information, as it is substantially less data.
The JSON-RPC API is a popular method for interacting with Ethereum and is available in all major Ethereum node implementations (e.g. Geth and Parity) as well as many third-party web services (e.g. INFURA)
A Provider is an abstraction of a connection to the Ethereum network, providing a concise, consistent interface to standard Ethereum node functionality.
A Signer in ethers is an abstraction of an Ethereum Account, which can be used to sign messages and transactions and send signed transactions to the Ethereum Network to execute state changing operations.
The Web3Provider is meant to ease moving from a web3.js based application to ethers by wrapping an existing Web3-compatible (such as a Web3HttpProvider, Web3IpcProvider or Web3WsProvider) and exposing it as an ethers.js Provider which can then be used with the rest of the library.