Gaining

Well if you're planning to start gaining I'd say money is always helpful. Food expenses increase the bigger you get. Luckily you can get fairly large clothes cheaply as long as you're not looking for dress clothes.
Obviously a sedentary job is preferable if you're starting to gain, but not necessary.
I'd argue that one of the best things you can do to set up for gaining is lay out your living space to minimize movement and maximize your chances to graze on snacks.

As to it being easy or hard that depends on you and your metabolism.

This is an interesting thread. I think encouragement is the most important. I know I would get huge if my wife, especially encouraged me to gain. So support is essential. I have a sedentary job already and food/money is not an issue. I am gaining but discreetly.