Is Bitcoin Core required for wallet projects?
Bitcoin Core is not required to do anything, but it is a useful software that you can use instead of trying to reimplement everything it does. Or you could use some other software that does the same thing. However Bitcoin Core is by far the most used and reviewed software compared to other node and wallet software.



You can use Bitcoin Core to create wallets and let customers send and receive to/from those wallets. However Bitcoin Core is not well optimized for having a large number of wallets (note that a wallet is not the same thing as an address), so it may not be the best for your use case. Of course, if you instead use the traditional model of one exchange wallet and just giving out depositing addresses to users, it's fine (users should not expect to "send from" "their" address).