Am I correctly understanding that all I have to do to use a ethereum light node (started with a syncmode=light) is to call regular ethereum api as described in https://github.com/ethereum/wiki/wiki/JSON-RPC ? So that I just call of those functions with eth_ prefix and I don't have to call the functions like GetBlockHeaders as described in LES specification:https://github.com/zsfelfoldi/go-ethereum/wiki/Light-Ethereum-Subprotocol-%28LES%29 ? So that geth will do everything w/o my help. Right?
LES protocol is the specification for the inter-node communication.
For user interaction, you can simply use the JSON RPC calls or web3 to query the node, however, not everything will be available like with the full node.
The Light Ethereum Subprotocol (LES) is the protocol used by "light" clients, which only download block headers as they appear and fetch other parts of the blockchain on-demand.