Can you please assist with the questions below:

1. Please describe Pareto optimality in full.

2. Please address the example below : Joe and Sue each hold a set of labor preferences and are allocated work accordingly. 

question: How can income taxation rules possibly result in Pareto improvements to their allocations? please provide a resposne with no less then 3 to 4 sentences

3. there is an article tDoing Business 2017  There is an article titled Doing Business 2017 which provides the information needed. I could not attach because of copyright. please pull link.

This article ranks countries with respect to their business friendliness. Regulation and taxation (a form of indirect regulation) are included as factors. Top 10 business friendly nations differ with respect to their precise regulatory and taxation programs. Although the Doing Business article is not necessarily claiming some countries provide Pareto superior regulatory/ tax systems, there is a presumption in the rankings that some regulations/ tax schemes are "better" than others. Why is it complicated to determine the Pareto superiority of how incentives are allocated? Please answer in no less than 4 to 5 sentences.