Is it normal to get so many log messages (3500 per hour)? What type of messages are sent?

This number of messages in syslog are normal, this is because it includeds all traffic for the LAN and WAN.

- Messages are sent when the LAN accesses the Internet.

- Messages are sent when someone on the Internet tries to access your WAN.

- Messages are sent for VPN, DHCP clients, PPPoE clients, PPTP clients when getting IP addresses from the ISP.