In what instances should goodwill be adjusted for impairment?

Client X operates in the US currently and is planning to expand operations globally next year. As a result, management is considering preparing financial statements in accordance with IFRS rather than with US GAAP.

Client X contacted you for clarification and recommendations regarding the following issues:

How the use of the LIFO method to value its inventories will be impacted if a switch to financial statements prepared in compliance with IFRS will be made.
Whether interest cost on construction of a new warehouse may be included in the cost of the new warehouse.
In what instances should goodwill be adjusted for impairment?
Provide a 150- word overview of each issue, followed by solid responses supported by research and proper citing.

Write a 350 word memo to Client X recommending the move to IFRS or the stay with GAAP, and why.