Google Sheets Email Reminders

Hi,

I need a Google Sheets + Google Apps Script based reminder system for my travel agency.

Requirements:
Google Sheet to manage airline group PNRs.
Fields: PNR, Airline, Sector, Seats, Payment TL, Name List TL, Status, Remarks.
Automatic email reminders for:
Payment TL (24h, 2h, 30min, missed)
Name List TL (24h, 2h, 30min, missed)
Dashboard showing:
Today's tasks
Tomorrow's tasks
Overdue TLs
Active & Closed PNR count
Automatic Google Apps Script triggers.
No duplicate reminders.
Clean and user-friendly Google Sheet.
Email reminders to a single Gmail account.
Complete source code and ownership.

Please let me know if you have experience with Google Apps Script automation and can build this.