Quote: "I am not sure if I can do everything you can do with C++, Classes mainly."
ABSOLUTELY! Classes and structs are a very powerful feature of c++. GDK is simply a wrapper for DBP. You make calls to GDK functions, but the rest of your program is however you prefer to write your c++ program.
Quote: "If I wanted to do this with strictly C++, not darkGDK where can I find 2D commands like in DBP or GDK like line and circle, etc...
This would require a different wrapper OR use DirectX. There is a "line" function within DX, but I've never seen a "circle" function--that you would have to write yourself (it's not that hard). The hard thing about DX is that you need to have a VERY firm grasp on how it works or you could get lost and loose interest quickly. I would stick with GDK until you grow out of it as a programmer-- it's a powerful and useful tool!
The fastest code is the code never written.