What is the source of initial transactions of bitcoin? Sorry, if I am wrong or silly!

It is understood that:

a) Satoshi Nakamoto sent the first transaction to developer Hal Finney on January 12, 2009, the genesis block contains 1,073 transactions and he got 50BTC as block reward, which is non spendable by design.

b) Coins are mined during block publishing.

c) A coinbase transaction must be 100 blocks deep before you can spend its outputs

d) Coins don't merge

e) For each transaction, sender should have group of input coins, whose sum should be greater than equal to sum of transaction amount and transaction fee.

What is the total amount of all those transactions and how they got BTCs for the initial transactions?
What is the total amount of all those transactions


You can see Bitcoin's genesis block here:

https://en.bitcoin.it/wiki/Genesis_block

You can easily examine early blocks by using the block height in any blockchain explorer. For example here 


  how they got BTCs for the initial transactions?


Mined blocks can be empty (contain no transactions other than the "coinbase" mining reward). I guess this can be the case when the mempool is empty or when all the pending transactions therein have unattractive fees.