Option 1 is the correct one.If we enable it then we can post unbalanced intercompany journals i.e debit <> credit for a balancing entity. For this we have to define intercompany accounts in setup-->Accounts-->Intercompany accounts, which will post the unbalance part to this intercompany account.
And if you disable it you cannot post the journals which are out of balance.
Let me brief you about both MRC and Multi Org. MRC stands for Multi reporting currency . which means you should have different SOBs, One must be primary and others are reporting. (max. 8).
Where as Multi Org concept is we will set up a organisation where we will have a Business group then SOBS then Legal entities then Operating units then Inventory organisations and lastly sub Inventory catagerory.. This set up will help to avoid multiple installations and have only one installation. We will attach all sub ledgers like AP, AR etc at Operating level and GL and FA at SOB level..
HR at Business group level.. There is a lot to discuss on this topic. please refer any avilable oracle material for more details.
No can not delete a budget
Yes you can update an existing account range in Budget Organization.
A budget against which accounting transactions are checked for available funds when budgetary control is enable for your set of books.