If you use PPPoE to connect to Internet, you will need the following options in the kernel (built-in or as preferably as modules) : "PP (point-to-point protocol) support", "PP support for async serial ports", "PP support for sync tty ports". The two compression options won't harm but are not definitely needed, neither does the "PP over Ethernet" option, that might only be used by rp-pppoe when configured to do kernel mode PPPoE.
If you require it, don't forget to include support in the kernel for your ethernet card.