R: You can deposite USD in iran , but you won't have the same deposit interest rate. For example if mellat bank is paying 17percent for one year deposit of Rls , it does pay 6-7 percent for the same year deposit of USD . Why ? Because RLS-USD drops around 10% every year and once every 15 years there is a risk of +70 % drop in one year . you want interest for investment ? Check out stocks and industry in Iran . here , investing in currency market is not so profitable , but investing in real assets and financials has almost the lowest risk in front of benefits.
R: the interest is guaranteed for only one year, banks in Iran lock the rate for only one year because rates change every year and this is only in Iranian currency. Foreign dollars can be exchanged in the country, many currency exchange offices. No bank has ever defaulted unlike other countries have, do the research. Opening a bank account in Iran only applies to Iranian citizens.