Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
Cache increases speeds by not requiring data be written to the drives immediately. If will increase the access times to your array regardless of what type of array it is. If you have a few users that aren't demanding, then you probably won't notice the difference.
Much of this has to do with...
Depends on what you define as "worth". If you only have a couple users, then you'll probably be fine. It's important to note that when cache is implemented, then typically a battery is a good safety net that you'll want to invent in as well.
if you don't have the battery, invest in a quality...
http://support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?idx=2177&modelname=CLP-315W&modelcode=&session_id=TpDnRBrH0JbBytgv8JDwkv31XjJwcj1Y5zPfHqXq60BVV4vPnsYt!-851570753!1589980556!1399423975118&from_osc=
maybe something useful in there. from the looks of it the "imaging...
Since the SBG6580 is a modem/router combo, the simple answer is no, you don't need the N56U. If you want to keep using the N56U, then I suggest setting it up as a WAP:
http://www.ezlan.net/router_AP.html
Setting up as a WAP will put everything on the same network, let you use the 3 leftover...
I had good luck with Crucial DDR1 Ballistix, not so much luck with the DDR2-800. The original version ran at 2.2v, and I had a number of them die in a few months. I RMA'd, and upgraded to the 2x2GB version, that ran at 2.0v, those died...but not outright. Instead if was painfully, BSoD every few...
Setting up a router as a WAP, pretty straight forward.
http://www.ezlan.net/router_AP.html
if that guide isn't enough, google "router as WAP"...there's endless guides