1-Yes you can, you just need to start ppoe server on lan interface, dhcp server can be enable when you install pfsense is askyng you dhcp enable for lan interface ?…and is asking for range, or you can enable it from web gui in SERVICES you have also ppoe server and dhcp.
2-You need to make new rule in firewall, after starting ppoe server wich will appear in rules ex WAN LAN AND PPOE server , click on ppoe server and you should select as gateway ->wan interface for internet acess(for ppoe clients).
For me it worked !