Q5) no not really, just the fastest way and expensive way so it goes fast, unless its like rc which i love so i USED to make deaths until u brought back wildy -.- meh.
i don't think that (for me,) efficiency is the driving force..it's whether i ENJOY the skill or activity available to train it.
profitability is definitely a factor, far more so than efficiency.
I use money to help train my skills, and profit is a great thing if I'm able to make profit while training.
I train my skills with a completionist idea in mind. I like to balance myself in skills, not be overpowered in one. I recently got all skills to 80+ and my next goal is 90+ in all skills.