I am not sharing an opinion in any way. I am just sharing for clarification of information.
Regarding "cash"
Bitcoin is a system "for electronic transactions without relying on trust," not explicitly digital cash in the way you mean.
Cash in the whitepaper is used to differentiate from the use of a physically printed or stamped cash or coins, a check, a debit or credit card, where a third party is involved in the transaction.
Regarding fees,
they are literally built into the system:
The incentive can also be funded with transaction fees. If the output value of a transaction is less than its input value, the difference is a transaction fee that is added to the incentive value of the block containing the transaction. Once a predetermined number of coins have entered circulation, the incentive can transition entirely to transaction fees and be completely inflation free.
Regarding transaction time,
this is also predetermined Constant that is set by the system using a variable hashrate difficulty:
To compensate for increasing hardware speed and varying interest in running nodes over time,the proof-of-work difficulty is determined by a moving average targeting an average number ofblocks per hour. If they're generated too fast, the difficulty increases.