I just do not understand a few things

1. When our AP's firmware replaced with DD-WRT or some firmware like this and set it up with chilli config , do we need to re-create a chilli server ? or is it enough to create a web & radius server ? I mean AP firmware is just a client or server

2. I have setup PPTP client on my AP's configuration. And it connects to my VPN server successfully. After that when i try on Router mode and set dynamic route for both side (WLAN & LAN and WAN) DHCP calls does not goes over the VPN is there any way to solve this ? we plan to create hot spot points over the VPN

Thanks