Since you already have a list of Ids (AcLst) you could query every Opportunity related to those Accounts, then populate a Map using the accountId as key and the list of opportunity as value.
Map<Id, List<Opportunity>> mapAccountIdOpportunityList = new Map<Id, List<Opportunity>>();
for (Opportunity o : [SELECT Id, StageName, AccountId,...
If you look at the documentation under Activate and Deactivate Currencies, you'll discover there's an option when you activate a currency to set the number of decimal places that are displayed. Per the docs:
To activate new currencies:
From Setup, enter Manage Currencies in the Quick Find box, then select Manage Currencies.
Click New in the ...