Focus on measurable KPIs: inventory accuracy, order lead time, on-time shipments, pick/pack productivity, and return processing time. Also verify carrier cut-off times, peak handling capacity, and SLA penalties. Where helpful, request historical performance reports and references to validate consistency.

Key cost drivers include: storage (per pallet/cbm), pick-and-pack labor and per-line fees, inbound receiving and inspection charges, returns handling, and carrier pass-through costs. Factor minimum monthly fees, seasonal surcharges, and any setup or integration fees into TCO assessments.

Closer proximity shortens delivery windows and enables more premium options (same-day, next-day). Expect improved carrier density and multiple delivery partners, but plan for urban congestion during peak periods. Consider micro-fulfillment or evening delivery partners to maximize SLAs.

Require WMS with real-time inventory API, order management system integrations (or OMS), EDI/RESTful APIs for carriers, and plug-ins for major eCommerce platforms. Confirm support for real-time stock updates, batch imports, and automated RMA workflows to reduce manual reconciliation.