In the last few years, Wireless Mesh Networks (WMNs) have become increasingly popular for the broadband enterprise networking and community networking. Due to the relatively small transmission range of mesh routers compared to cellular networks, mobile stations in WMNs may experience frequent handoffs. Therefore, an effective mobility and association management has become vital to the performance of real-time applications (e.g., VoIP) over WMNs. In this work, we introduce a cross-layer association scheme for WMNs, which uses the end-to-end airtime cost as the association metric and provides the mobile stations with the highest end-to-end network performance after their association. We then introduce a backhaul-aided seamless handoff scheme, which takes advantage of the wireless backhaul feature of WMNs and thus achieves low handoff latency. Finally, we describe the 700MHz WiFi-based WMN testbed that we have deployed under both indoor and outdoor environments, including open space and a Louisiana swamp with dense cypress trees.