The skills Spot/Listen/Search will be combined into Perception like in pathfinder.
The D20 Modern system uses Action Points. You get a number of action points per level, based on your class, and can spend them once per round to add 1d6 (or more for higher levels) to any attack, skill check, ability check, or saving throw roll you make. You do this after you roll, but before you find out whether your roll was high enough. You can also use them to activate class abilities.
That's all by the book. http://dmreference.com/MRD/Basics/Action_Points.htm
Here's the house rules part:
You can spend an action point to bend fate to your advantage. Not in huge ways, the guy you're fightings not going to drop dead from an aneurysm due to it. Maybe your character got caught and is tied up. You spend an action point, and convince me that since your character is a little paranoid, and never went anywhere without a weapon, that he had a small knife taped to his back that you can use to escape.
The DM will also award Action Points for superb role playing. The group can also vote for someone to receive an AP for doing something awesome.
2 Free action points to any player that sells Derek's bigoted insane preacher character into slavery.
Like your individual characters have Action Points, your kingdom in the making will have Fate Points. You will have 1 Fate Point each session. (I might modify this as time goes on).
You can use this Fate Point to help you with the survival of your Kingdom. If your followers are not having much luck finding enough food to survive, you spend a Fate Point, and maybe one of your foraging party will come across a train car full of wheat, or find some other supply of food to get you by. Or maybe you are unsure where would be a good place to settle, spend a fate point, and a couple of your followers might have some suggestions on the subject.