Google considers relevancy a major criteria while ranking websites. Hence a niche backlink from a relevant source is highly valued than a backlink from a general source. This enables a business/user to target specific clients only and build quality and relevant backlinks thereby improving their SERPs gradually. Niche links are valued highly and is a very good link building tactic
Yes that's right. You can make a lot of money if your planning and execution functions are efficient.
Lots of variables to consider, but none is bigger than the addition the new .DIRECTORY top level domain.
I prefer to set myself mile stones. 100k in the first year? Unlikely without spending a substantial amount of money.