Bitcoin cannot replace the credit card today, simply because of it's 10 minute transaction time. Impractical in real world situations especially since it takes a few seconds(1-3) for you to be able to transfer money on a credit card, unlike Bitcoins 10-40minute wait...
This.
Incorrect. The amount of money/time needed to fool the network with a 'fake' transaction is worth way more than the $5 coffee your trying to buy. Even if you are buying something like a massive house for a million dollars, if you cant wait 10-30min for the transactions to confirm then you have some serious priority issues.
Also a 'faster' network will need more confirmations to be as secure as a 'slower' network. Ex: a network with 1min block times vs bitcoin with 10min block times: The faster network would require 10 confirms to be as secure as 1 confirm on the bitcoin network.
EDIT: I also believe that the time to actually transfer funds with a credit card in in the area of weeks, not seconds. The merchant has to sit on the transaction for a pretty long time before they actually get money from the CC company.