The only one of those that I can answer definitively is the last one. The first two depend on several factors. Generally, if you're following content trends and write with authority you can expect a certain % of your articles to sell right away. The rest will sit. CC claims that 70% of articles that you get approved will eventually sell. This feels about right.
If you're writing niche articles you'll have to wait longer. None of my recent Forex articles have sold yet and I'm something of an expert in the field. It's just a bad time for Forex content, I guess.
I recently submitted a social media marketing article and it sold right away.
Regarding price: if you're good enough to get your content past their editors, you need to be charging at least 10 cents per word. I price a 500 word article at $49. If someone comes along who badly needs that content, they'll pay for it. It's not worth my time to price lower than that or accept offers lower than that because CC is taking 35%, which leaves me with just $30.
If you have a well-researched, well-written 1000 word article that's in an in-demand niche, feel free to charge $100 for it. It all comes down to the right person coming along to buy it anyway, so you'd be cheating yourself if you charged less.
Demand is king. The people who shop there know that CC articles cost real money.
CC can be great income if you can write 5 a day on topics that are selling. The challenge is A) working up the will to work that hard on spec, and B) getting all of those articles past their extremely strict editors.
I suggest using Scrivener to outline your articles. It's a HUGE time saver. You can find it online, but it's only $40, so support the developer if you can. It's just one guy developing it.
One thing to understand is that CC clientelle are really fickle. I recently wrote a well-researched article about how to make addictive games like Minecraft. I did a lot of research for it. I was sure it would sell because of the subject matter, but it hasn't. I just have to wait for the right person to come along. When will that be? No idea.