Why should managers use study supply, demand and their elasticities?

Assignment # 1 (Managerial Economics Textbook )
1. Why should managers use study supply, demand and their elasticities?
2. What is the difference between Accounting and Economic Profit?
Case Study: 
3-2 House Closing       
You’ve entered into a contract to purchase a new house, and the closing is scheduled for next week. It’s typical for some last-minute bargaining to occur at the closing table, where sellers often try to tack on extra fees. You have three options for the closing: (1) attend yourself, (2) send an attorney authorized to close only per the previously negotiated terms, or (3) pre-sign all the closing documents per the current terms and not attend the closing. Consider each bargaining position; which position would you go with and why?