Presumably, in El Salvador, salaries would be denominated in BTC. That's the only thing that'd make any sense. (And, barring external regulatory force, it's very likely to be what a free job market where employees mostly spend BTC would move to doing.)
I don't see why they would be denominated in BTC, given that BTC will be legal tender alongside USD, and USD is a much more stable currency.
Making it a legal currency won't even force anyone to accept it. As far as I understand, it will simply mean that the government will accept payments in BTC.
Seeing how not being able to print more money when you need it worked out for the government of e.g. Greece, I would be surprised if El Savlador chooses BTC for paying its debts.
Imports and exports are not priced in BTC though, in the same way that there aren't really imports or exports priced in gold.
Given the massive volatility of BTC it presents a massive opportunity for arbitrage that mostly has downsides for consumers who want stable supplies of goods.
