Excel Overhaul & Automation Needed

My current Excel workbook has grown messy and unreliable, so I need it taken back to a clean, efficient state. Every sheet must be reviewed for three key areas:

• Data entry & correction – verify existing records, add any missing items I will supply, and most urgently refresh all drop-down lists so they reflect our latest categories without breaking the dependent ranges already in place.
• Formulas & calculations – replace scattered basic formulas with consolidated, well-documented logic. The workbook depends on advanced elements such as nested INDEX/MATCH combinations, array maths, and several task-specific macros; these must be re-written or optimised so they run quickly and are easy to maintain.
• Visual formatting & design – once the numbers are right, the presentation has to be too. Consistent cell styles, conditional formatting that highlights exceptions, and a tidy summary dashboard will make the file usable for non-technical staff.

Deliver a fully updated .xlsx (plus macro-enabled .xlsm where applicable), clearly commented VBA modules, and a brief changelog so I can trace what was altered. If anything in the legacy file appears unclear, let me know early so we can decide whether to keep, tweak, or retire that element.