As I'm saying, that's unrelated to PPPoE, otherwise every PPPoE users would be affected.
Cable users who use DHCP have worse latency than FTTH or Fastpath DSL over PPPoE users, as Docsis 2/3 adds 8-10 ms of latency at the first hop.
PPPoE encapsulation has nothing to do with NAT.
That's incorrect. PPPoE merely transport packets between the router and the concentrator, the TCP/IP packets within it are unrelated.
Again, that's incorrect. I have port forwards setup to receive remote backups from a VPS, and another port forward to allow my employee to remotely access a VM here. PPPoE, once again, has nothing to do with port fowarding, different layers.
I don't think you really understand what PPPoE is, and what packet encapsulation does.