If I want to do the usb install on the hardware listed above, I would need a separate video card or would not?
No. Your question was clear, and I thought my answer was as well--the X10SL7-F has onboard video (what part of that answer was unclear, or what part of your question did that answer miss?). And if you didn't believe me, the product page on Newegg that you linked to says so as well, in the Specifications section. It isn't especially good onboard video, but it doesn't need to be--you're building a server, not a gaming machine or CAD workstation.
how would I get the IP to access the server if I could not see the server on initial boot up?
Through the DHCP leases screen of your router, or through an app like Fing on your smartphone, to give two examples. I'm not sure if FreeNAS is using mDNS; you may simply be able to browse to freenas (or freenas.local), in which case you wouldn't even need to know the IP.
@pirateghost is addressing a somewhat orthogonal issue, which is that you don't need to attach a keyboard and monitor to your FreeNAS box at all--via IPMI, which that motherboard supports, you can do it all over the network. IPMI also lets you attach media (like .ISOs) remotely, so you don't even need to burn the FreeNAS ISO to a CD/USB stick to install it.