I second the rec for a canister over HOB if you want to go planted. I suspect if you start with the Emperor, at some relatively soon point you will regret it due to the surface agitation and noise. Moreover, no need for a bio-wheel in planted tank.
As far as which canister, I know how frustrating the decision can be. I just replaced my HOB bio-wheel with an Eheim ecco. I didn't think the prices between the ecco and competitors were all that much, so I figured I'd go with the eheim name. Eheim classic canisters are only a bit more expensive. The Eheim pros start to get pretty pricey, tho.
If you splurge on an Eheim out of the box, it is pretty unlikely that you will quickly outgrow or become dissatisfied with it. And tho pricey, they seem to last pretty well (as well as possibly retaining some resale value).
Re: CO2 - what George said. If you do not have any canopy/light for your tank, I would suggest that you consider going with something that can be expanded should you wish to. For example, you might be able to start with a single 96W from AH. http://ahsupply.com/96watt.htm
At that level, you could have decent results w/o CO2, tho you would be limited in the plants that would thrive.
Then, if you decide you want to step it up at some later point, you could add another 96W and pressurized CO2. But plan ahead, so your initial canopy will accommodate such expansion.
It really sucks to buy something, and then in a relatively short period have to toss that it working perfectly well, but just not keeping up with your developing interests.