1 - If you're planning on using ethernet and PCI-E in your final design, yes this is a good board. So is this one:
http://www.altera.com/products/devkits/altera/kit-siv-gx.html 2 - Source code is not provided for the Ethernet and PCI Express cores.
3 - There are PCI Express reference designs but I don't know of any specific Ethernet-to-PCI Express designs.
4 - You can use the Ethernet and PCI Express IP cores without buying a license but they timeout (or you have to keep it tethered to your PC). If you decide to, you can purchase a license for the IP Cores from Altera (you still don't get source code).
There are also boards from Xilinx and Lattice that may meet your needs.
Jake