apex 2 doesnt contain an energy booster. apex 3 has the added caffine boost. apex 2 puts more focus on the breakdown of fat, whereas apex 3 puts more focus on fat burn. i would stick with the apex 3. when i trained at 24, i saw a lot more results with apex 3 than i did with 2, especially for someone your size. just make sure you take it like medication and stick to your work outs and diet.
you shouldnt have too many size effects, just the same as a cup of coffee.
make sure you get it when its on sale though. if its not on sale the beginning of the month, it will be the 2nd half.