Honestly, it is easier to lose fat with a supplement like HOT-ROX. But, what are your stats and training history? I wouldn't recommend starting off with something you're not going to want to use all the time. In my opinion, HOT-ROX and thermogenics should be saved as a boost when things are getting slow. If your diet and training are right and you're a beginner, weight is going to fall off you, HRX or not.
Diet: Read more about this. You're not just limited to tuna. And don't skip your yolks. Eat all kinds of unprocessed meats, vegetables, fish/flax/olive oils, and the occasional fruit. Can't go wrong.
Do you have any specific goals? That'll make your questions a lot easier to answer.
As a beginner you want to stick with the staples that definitely work and hardly need to be cycled (however, I believe its best to vary everything): Surge (post workout), BCAAs (pre/during/post workout), Metabolic Drive (when you can't get a meal in), Flameout (with meals), ZMA (prebed), creatine (post workout). Even this is kind've a lot of stuff, but if your training and diet is right already, and you're ready to spend some cash, you should be very happy with your results.
p.s. While I support Biotest most of the time, I get great (the same) results from bulk BCAAs which are SO much cheaper.