your best bet for that size is to do a sump. Canisters are superior for filtration as there is never any bypass and the water is forced through the media. Wet/dry sumps are best for biological filtration and create a more stable environment because sumps are usually a decent percentage size of the tank its going on. You will spend more money on multiple canisters then a single wet/dry.
wet/drys are a complicated animal to explain, its very to visualize unless you see it first hand. If your tank isnt plumbed or going to be (aka drilling a hole at the water line so the water overflows down a pipe into the sump box) you need an overflox box, generaly a CPR Aquatics overflow which pull the water up and over the tank in a little box and down the pipe as shown here
http://www.cprusa.com/products/overflows.html. This is a nonevasive way of doing it so you dont have to put a hole into your tank.
Sploke would be best from here to explain how the rest of a sump works. If you cant make one yourself you can always buy one.
As for lighting, i am a Current USA person and like the nova's. You have a 180 gallon tank and would need to 36 inch fixtures or 1 single 72 inch fixture no matter what company you go with. You need 540 watts for 3 wpg (watts per gallon), 360 for 2 wpg, 180 watts for 1 wpg.
Since you want a medium planted tank (what it sounds like) thats about 2wpg. Now keep in mind that these lights are expensive, having to buy additional fixtures or a larger one can get expensive quick and you may want o consider a 540 watt fixture which has multiple switches to control the bulbs so you can create 1wpg 2wpg or 3wpg.
this fixture will yield 2.6 wpg with all bulbs on but you could turn half them off and get 1.3 wpg. Keep inmind for this one you would need to change out the actinics with freshwater bulbs whatever spectrum, most likely 6500k since these are good for growing plants.
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3733+13822+18700&pcatid=18700
