Trade seemed a lot better in GCII per my recollection. For this reason I don't do a lot of trading. Tourist income is great and well worth pursuing.
There are some trade bonuses by building star bases along your trade routes but I have not gotten into building this up.
Anomalies are nice if you like the boost they give you. If you feel they are OP you can make them rare and even omit them, I think. I haven't heard much complaint about the anomalies so I guess the choice to make them rare works for those who are after the max challenge.
My current preferences are the big maps, normal difficulty, 8-9 AI, Occasional stars, common planets, occasional habitable, abundant anomalies, abundant resources. I enjoy building my empire on culture, military deterrent, wealth and diplomacy. Most of my wins are influence or diplomatic. I play the game for a casual distraction. I am not into an intense challenge.
If you are after the most challenging game out of the AI, you should try playing with abundant habitable planets. The AI thrives on colonizing and they will overwhelm you if you don't keep up. Setting anomalies and resources to rare also adds to the challenge. I am sure others will give you better hints on enhancing the challenge.