Can you attach a port extender to it to get more usb ports?
Yes, I use a 10 port USB hub and all ports work fine.
I recommend a powered hub with at least 2.5 amps. The hub will power the Pi at the same time so you can run without a separate supply.
>>> Can you attach a port extender to it to get more usb ports? <<<
The Pi 2 has 4 USB ports but I’ve added an extender for 4 more ports. No problem: the UNIX operating system picks it up and integrates it into the system automatically on power-up.