Some Help (tournament challenges, leveling, and gold)

So to start off I'll mention that I do not spend money on the game for gold, however I am relatively active with playing about every day and trying to get gold as often as possible through challenges and videos or other things.

That being said I currently have mainly 3.5-4 star players (2 3 and 1 4.5) and have never really understood the tournament challenges and was wondering if I am missing out on much. Are they very beneficial or does it really just matter if you can get a good group?

Next, leveling. I assumed leveling is good and beneficial because other than playing harder players I haven't noticed much of a difference and it gives you awards for leveling up such as draft picks and gold (the main reason I have been trying to level). However, I saw a post recently that made it sound like leveling is bad. The only issue is I don't understand how I am supposed to get significant amounts of gold without leveling up. 200 or so gold may not seem like much but when you only get 50-100 from other things and don't buy it it helps and adds up after awhile.

Finally, what is the most beneficial way to spend gold? I have bought a handful of #1 picks and a couple multi drafts already because I feel like my players aren't that great and I want to get better ones. Although I have seen that saving gold for fan rewards and spending it on upgrades is the best thing to do. I haven't had the chance to spend gold on upgrades yet as I'm still using cash. On the other hand at what point should I spend the gold for fan rewards, 10,000?

I felt as though I had a decent idea, feel, and strategy for the game but after looking on the forums more and playing a little further on I'm starting to feel like that is far from true. Advice on any of these things and others would be awesome and much appreciated! Thanks!