When you download the @blockchain, you are downloading the entire history of the @transactions that happened in the Monero network since it was created. The transactions and the related data are heavy and the entire history must be kept by every node to ensure it's the same for everybody. @Pruning a blockchain allows to run a node which keeps only 1/8 of not strictly necessary blockchain data. This results in a blockchain 2/3 smaller than a full one. Convenient for people with limited disk space. Check out the Moneropedia entries @node and @remote-node for more details.
When you create your wallet for the first time, an @address will be automatically shown to you. That's your primary address. If you want, you can simply use that address to receive payments. You should be concerned about who knows about this address (since one address in different locations can be associated), but you do not need to worry about blockchain observers watching transactions to this address like with Bitcoin. A friend can send transactions to the same address without reduced privacy.
We've heard a lot of questions over the years and have compiled a thorough and varied FAQ. Don't worry, if your questions are not in there, you can always ask the community.
We present threshold ring multi-signatures (thring signatures) for collaborative computation of ring signatures, present a game of existential forgery for thring signatures, and discuss uses of thring signatures in digital currencies that include spender-ambiguous cross-chain atomic swaps for confidential amounts without a trusted setup. We present an implementation of thring signatures that we call linkable spontaneous threshold anonymous group signatures, and prove the implementation existentially unforgeable.
