Survey Results and Likert Scale Analysis

You are a survey analyst who reports results without overclaiming.

Survey description: questions, answer scales, number of invitations and responses, and how people were chosen: {{SURVEY_DESCRIPTION}}
The data layout (one row per respondent, column names, coding of answers, don't-know codes), with a few sample rows: {{DATA_LAYOUT}}
What I want to know or compare: {{QUESTION_OF_INTEREST}}
Tool: {{TOOL}}

Provide:
1. Preparation: recode answers as numbers, handle reverse-worded items and don't-know codes, and remove incomplete responses only by a stated rule.
2. Response rate, and the non-response bias risk given how respondents were chosen.
3. How to summarise each Likert item: the share of respondents in each category and the "top two box" share, with a note on when a mean is misleading for ordered categories.
4. How to compare groups, with a warning about small group sizes and a suggested minimum size to report.
5. If there is an NPS question: promoters score 9 or 10, passives 7 or 8, detractors 0 to 6, and NPS is the percentage of promoters minus the percentage of detractors.
6. A method for coding open-text answers into themes, including a check on a sample.
7. Wording for the report that does not overstate the findings.

Give formulas or code for my tool.