I'd grade the proposed list of questions and their confidence scores around an 8.0. Here's a detailed evaluation:

### Strengths:
1. **Relevance and Comprehensive Coverage**: The questions cover a wide range of aspects related to the process, including frequency, performance, approvals, and rejections, which are essential for understanding and improving the process.
2. **Diverse Angles**: The questions address different angles like the roles of various approvers, steps that involve rejections, and cases where declarations are resubmitted, which shows a good grasp of the complexity of the process.

### Weaknesses:
1. **Precision and Specificity**:
    - The confidence scores for some questions seem a bit arbitrary and not always justifiable. For instance, the confidence score for "What is the most common reason for a declaration to be rejected by the supervisor?" might be lower due to the potential variability in subjective reasoning.
    - Questions about the median performance (questions 4 and 10) could be less useful in a dataset with a wide performance range, and thus the confidence scores could be revisited.
2. **Missing Key Process Aspects**:
    - The list assumes the correctness of frequency and performance measures without validating the data or considering potential outliers and anomalies in the process. Including questions that look for data anomalies or variations could add value.

### Grading of Each Confidence Score:
1. **Most Frequent Process Variant**: Well-founded score (0.95) due to clear frequency information in the data.
2. **Least Frequent Process Variant**: Similarly, a substantiated score (0.95) due to the same reasons.
3. **Average Performance**: High confidence (0.90) is reasonable due to the calculable and straightforward nature of averages.
4. **Median Performance**: A bit more challenging due to data distribution, so the score (0.85) feels slightly high but acceptable.
5. **Declarations Saved but Not Submitted**: The score (0.90) makes sense due to clear saved vs submitted frequencies.
6. **Supervisor Rejections**: Reliable (0.85), as multiple variants show clear rejections by the supervisor.
7. **Rejections by Administration**: High confidence (0.95) as the data distinctly shows these cases.
8. **Common Rejection Reasons**: More subjective and requiring detailed analysis, so a score of (0.80) is reasonable but could be lower.
9. **Number of Approval Steps**: Logical approach, and the score (0.85) seems justified.
10. **Median Number of Approval Steps**: Similar consideration as question 4. Thus, the score (0.80) could also be a bit optimistic.
11. **Budget Owner Approvals**: Clear in the data, so a high score (0.90) is justified.
12. **Average Performance with Budget Owner Approval**: Thorough (0.85) but depends on data variation.
13. **Rejections by Pre-Approver**: High confidence (0.95) due to explicit mentions in the data.
14. **Handled Without Being Saved**: Makes sense, but (0.80) might be slightly high due to potential unnoted subtleties.
15. **Rejection Reasons by Supervisor**: Subjective, given complexities, so a score (0.75) feels accurate.
16. **Median Performance with Budget Owner Approval**: Reasonable based on data (0.85).
17. **Resubmission After Rejection**: High confidence (0.90) due to clear process flows showing resubmissions.
18. **Average Performance Without Budget Owner**: Logical (0.85) based on data review.
19. **Supervisor Rejections Later Approved**: More complex, so a score (0.80) feels good.

### Conclusion:
Solid coverage of relevant points, thoughtful questions with mostly appropriate confidence scores. A few tweaks could improve the precision and insights derived from the questions, but overall, it is an excellent approach to understanding and analyzing the process.