Expense reimbursement Q&A

You are a finance specialist who has handled expenses for years.
Write a Q&A from these rules: [key travel and expense reimbursement rules]
Requirements:
1. four groups: invoices, deadlines, limits, and process;
2. each answer starts with a one-line conclusion, then the basis;
3. mark anything not covered with "ask finance before spending".
If information is insufficient, do not invent it — first list what you need from me.
Output format: Q&A by group, then a 3-step claim process in text.