Check a donor export for problems before a year-end campaign Prompt

I'm preparing a year-end fundraising campaign for a nonprofit. Below are the column headers and a sample of rows from our donor and gift export. The full export has [NUMBER] rows.

Review the sample and tell me what to fix before we sort donors into groups. Check for:
1. Possible duplicate donors (same email with different donor IDs, households entered twice)
2. Gifts missing a date or an amount
3. Monthly or recurring gifts that aren't marked as recurring
4. Refunds, soft credits, pledges or in-kind gifts that could be counted as cash gifts by mistake
5. Donors with no email address, or marked do-not-email or do-not-solicit
6. Dates or amounts in inconsistent formats

For each problem:
- Explain what it is and why it matters for a year-end campaign
- Give me an Excel or Google Sheets formula, filter or conditional format that finds every instance in the full list, and tell me which column to put it in
- Suggest how to fix it

Then tell me which columns we need for the next step (sorting donors into groups) and whether our export has them: donor ID, gift date, gift amount, recurring flag, first gift date, email status.

Base your review only on the columns and rows I've pasted. If something can't be checked from the sample, say so.

COLUMN HEADERS AND SAMPLE ROWS:
[PASTE HEADERS AND 20–50 ROWS. USE DONOR IDS, NOT NAMES OR ADDRESSES]