Are there any benefits to playing on higher difficulties?
Enemies don't always run away after firing a single shot anymore, and you can start the game with sadism/masochism points. In exchange, everything else is harder to do. I think one of the mechanical changes in v.7A is going to be more customization options for the difficulty though.
As long as you're not playing on Prisoner difficulty, all you really need to keep in mind is: lower Order = more subsidies. So keep it low (just not so low that a random riot can end your game, so 25 is good) and of course avoid Edicts that increase your expenses. The first set of "Publish" edicts is also recommended, not just for income but because they unlock status information.
Keep in mind that low order means more waves of enemies in every fight; don't let it get low enough that you're actually in danger, and keep a close eye on your fatigue.
You can get money by fighting/fucking the guards outside your office every day, but this is a trap. Every time you do this increases their aggression and power, so if you do it too much you end up with superpowered guards joining every fight on the prisoners' side.
After you subjugate level one, you get several options to produce minor income by putting prisoners to work, and you can put on a waitress costume to earn a significant amount every day from booze sales and tips. Subjugating level two gives you even more options to reduce costs and increase income, on top of the subsidy boosts you get from every defeat of a floor boss.
My best advice about money is to take things pretty slow; if you're not personally overspending then the balance of order to subsidies tends to self-stabilize so you're never rich, but you're never in serious danger. Except in Prisoner Mode.
Oh, and check your equipped title. Every day between when you start the game and when you remember to change it away from the starting nonsense costs a big pile of gold for no reason.