Inflation will not affect your Credit Card spending. Once you purchase a product or service with your credit card, you are locking in the Peso price you are signing the voucher for. That charge will be applied to your credit card statement at that days spot ForEx rate. The rate of exchange applied will be the official rate, which currently is approx. 4.60 Pesos per dollar, minus the ForEx fee that your credit card agreement has established with you.

As for getting Dollars back when you return.... this is in theory possible, but I would not bother with it in practice as you will just incurr in an exchange rate loss.

Just use any excess Pesos to pay for a portion of your Hotel bill when you check-out. As for taking back any Dollars you brought into the country in cash: yes... sure you can take those back, as long as you dont have more than $10,000 in cash... which btw you cant have more than that when you come in either (thats pretty much a rule that is universal, its not an Argentina thing).

IMPORTANT: when you arrive at EZE, do not use the Global Exchange Crooks to trade your Dollars... please read the various threads on this forum for further information.