1. Excise duty in charged on production but payable when goods leaves factory premises, so when goods are produced but not yet dispatched, excise duty is levied / accrued but not yet payable. So we pass this entry Excise Duty A/C Dr XXX To Provision for ED XXX  for ED on closing stock/ Expense part goes to other expenses. 
2. Analytical Procedures:- Ratio of excise duty to production value should be near official excise rate, if its near that then it proves it is proper. 
3. Yes gratuity account will ultimately go to P&L
4. Questions will be straight forward see questions in PM

excise duty on goods dispatched is transferred to p&l but ed on stock is shown as Current Liabilities ?

Accounting Entry 
Excise Duty on Goods Manufactured and Sold 
Debtors A/c Dr 110
To Sales 100
To Excise Payable 10
Excise Duty on Goods Manufactured But Not Sold 
Excise Duty A/C Dr 10
To Provision for Excise Duty A/c 10
Closing stock credited to p&l will included excise duty of Rs 10, effect on p&l will be nil.
In balance sheet closing stock will be higher by rs 10 and provision will be higher by rs 10
This entry is passed so that excise duty is booked as expense in current year , if such entry is not passed ed of current year goods will get booked in next year.
 
This is core accounts knowledge , you should remember that as production took place in current year expense should get booked in current year only, for audit purpose.