If your budget can afford it, use both. If not, use the one that is MOST commonly used. But don't worry about it because we optimize pages in all three cases, so you only need to send us lower case terms. This is the hardest question to answer.
Search engines work in cycles.
If you missed a cycle you have to wait for the next one. So the real answer is we don't know. But from experience, we can tell you that there will be some results within 30 days, more in 60 days, more again in 90 days. A. Unfortunately, there is no guarantee on providing any amount of traffic on any site. If anyone guarantees you traffic, it's like saying they guarantee you to put money in your pocket no matter what.