Weird trixbox CE DHCP and TFTP behavior

The trixbox 2.6.0.5 system with:
- eth0 has a static private IP and connected to a wireless Internet router with ports 4569UDP, 5060TCP and 10000-2000UDP forwarded to eth0. The router has DHCP server enabled to serve IP addresses to computers.
- eth1 has private IP with DHCP server enabled on this interface only and supplies IP addresses to IP phones via Ethernet and wifi SIP phones via Cisco 1242 AP.

The defualt gateway on trixbox is the Internet router's private IP. No routing installed through trixbox and no firewall enabled (both interfaces are private).

Problems:
- The computers connected to the Internet router are getting served IP addresses by the trixbox DHCP server on eth1 although eth1 is not connected to the Internet router, DHCPD is configured to listen on eth1 only, and the Internet router has its own DHCP server. I have to turn off the trixbox DHCPD in order to let the Internet router's DHCP server do its work. How can DHCP requests traverse trixbox from eth0 to eth1 (broadcasting through the PBX?)
- The trixbox TFTP server is not serving files to certain Polycom 650 phones and wifi phones. I had to install a 3Com TFTP server on another machine on the LAN to serve those phones. The weirdest thing is that those phones can be served firmware files but not CFG files or vice versa. Nothing consistent. Is there a safe way to remove the trixbox TFTP server and install something else on the box without disrupting anything?