In the context of Java programming, discuss the significance of having a thorough understanding of variables and data types. Compare and contrast the various data types offered in Java, including both primitive data types and reference data types. Additionally, explain the distinct roles played by variables and data types in the storage and manipulation of data. Illustrate your points with relevant examples to reinforce your explanations.

Elaborate on the concept of operator precedence in Java and how it affects the evaluation of expressions. Discuss how understanding operator precedence can help in avoiding potential errors while writing code and improving program efficiency. Demonstrate your understanding by providing examples that highlight the importance of considering operator precedence in Java programming.

In the context of Java programming, engage in a comprehensive discussion regarding the significance and diverse applications of conditionals. Analyze and compare the distinct types of conditional statements available, including if$-$else, switch$-$case, and ternary operators, focusing on their syntax, functionality, and use cases. Examine the advantages and limitations of each conditional statement type, while differentiating the scenarios in which they are most effective. Elaborate on the factors that influence the selection of one conditional statement over another.