It's not. Don't worry. Mass effect is never as complicated as it seems. And this one was made simpler then the previous by removing a.cap. you can max out all of your stats. Basically, find a gun you like. Use it. Other guns won't be inherently better because of the weight system. So don't be afraid to stick to a good gun, or try new things. Attachments are basic. More range, stronger melee, wider spread, less spread, more stability. Etc. Find a power you like, and see what it combos with. Abilities you start with can carry you through the game if it's anything like the previous games. Additionally, read what the final version of your abilities will be to know ahead of time of you wanna spec it. Have fun. Don't worry about complications. Unless u throw on insanity difficulty, or platinum or gold in multiplayer's case, mistakes in spec won't hurt too bad.

I'm digging the different roles for multiplayer.