I have setup the private ethereum block by doing following steps.

1- Initialised same genesis.json on 2 systems.

2- Started geth console by using same network id.

3- Added these two systems (node) by adding them as peer using admin.addPeer command.

Now i am able to do all the transactions. 

**Questions** :

1- Now this private blockchain is ready and if i have to add any new user do that mean i have to start a new server and on that server i have to follow above steps. ? 

2- How do these wallets (ETH wallets) are setting up their infra? Do they have one server which is connected to public ethereum blockchain? and any new user who is joining/buying-ether from these wallets is basically getting added in these wallets account not as a new peer ?

3- From above two questions i have figured out that it is basically there are so many exchanges or wallets who are connected as peers to public block chain and individual who is buying or selling using these wallets are basically accounts of these wallets. (added as new account eg: personal.newAccount("xux"))

I am new to blockchain and trying to understand the infra how it is being setup so that i can replicate same for my private blockchain. Please correct me if i am wrong and please clear my doubts.

Thanks In advance.