Sorry, I don't have experience dealing with large amount of data like what you mentioned above... Perhaps others can advise on this. That being said, there is a 1GB DDR3 memory on the FPGA and HPS side respectively that you can probably manage using DMAs and a NIOS/HPS. I've seen an FFT implementation here (does not process continuous data, just a snapshot) but maybe you can get some idea out of it:
https://rocketboards.org/foswiki/view/documentation/ws1introtoalterasocdevices Regarding the SATA peripheral - yes you are right that this board does not have it, unless you use one of the expansion card like this:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?language=english&categoryno=67&no=489 But then it will probably increase project complexity. Regarding Ethernet/USB, there is only RJ45 jack/USB headers on the HPS side - so again, you can instantiate an Ethernet IP on the FPGA side, but there is no external PHY to hook it up with (unless of course, more add on cards are used).