Some problems with video filterin on FPGA

We would like to write a code for video processing on Development board with FPGA (Xilinx and Altera). On this board no Signal Processor, but I read documentation and undestood, that processor can be realised on FPGA by using processor core. Do you know, how does many percent of all Logic Elements this “software processor” use, and how shall we write code for this processor? Do you know any programs, that can convert code on C to special code for FPGA (for example Verilog, Vhdl etc.)? And do this programs have a Debug code features (for example, we would like to know values on each FPGA out in smth. time momemt)?
Can you advise any emulators of FPGA, which can be run on PC?
Next problem: we must to filtering video. We have a video file on PC, and would like to have a Video file after processing. What interface, which can be on Development board, is more better to this? We think that is a PCI/PCI-Ex or Ethernet, but you may be have another opinion.