Amplifer setup?

I have an 89 cefiro and and have just got an amp that is 1800w max 4/3/2 channel. head unit has two sets of rca's coming out of it marked front and back. Do I have to hookup both sets to my amp or only the rear connections My amp has incoming and outgoing for the rear and incoming for the front. I only intend on using this amp for one monster sub. The advertisment with my amp says that if I run it at 2 Ohm I can get 3600 W max out of it. Does that sound right. At the moment I am only getting one sub and plan on using my amp as two channels and running one channel to each side of my dvc sub. this will only have it running 4 Ohm. Or I can have one channel running both sides of the sub at 2 Ohm with an empty channel. Any advise on this would be appriciated

Bryzaa 

sorry it is a Saga audio Usa amp HG-7450 1800w Max and a boshman 12" dvc sub 1500 W Max model ZD12XAL

Cheers

the amp is 65w x 4 @ 4 Ohm, 125w x 4 @ 2 Ohm, 180 x 2 + 400 x 1 @ 4 Ohm 500w x 2 @ 4 Ohm it doesn't say what it is for 2 channels at 2 Ohm which is what i want out of it, It gives me specs for 2 Ohms so am I to assume that it is stable there. The Sub is 750 rms and it says that is per each voice coil so I think that is 1500 rms total, or is it still 750? anyway I only want to run the 500w per channel to the one sub. I bought both online and have included links to their websites so if there is anything there that may be helpful.

Link to amp page is http://www.trademe.co.nz/Browse/Listing.aspx?id=51553361

Link to sub page is http://www.trademe.co.nz/Browse/Listing.aspx?id=52777700

p.s.  Noone here has heard of that brand of amp either I think it is chinese