Yes a node in the Stellar network doesn't need to know all the other nodes in the whole network and adding and removing nodes is a fluid and open process but yes there must be some transitive overlap in the quorum slices people choose. The details would be better explained in the paper.

All the coins(lumens) exist when the network starts up. The Stellar Foundation is distributing them in the following way: https://www.stellar.org/about/mandate/#Stellar_distribution