I have a small antifreeze leak under my car, but it's not so bad?

Head gaskets can leak in a number of different ways. That will cause overheating perhaps 25 percent of the time. An unaddressed coolant leak will make it impossible to tell if the level in the reservoir is going down due to that leak or a leaking head gasket. The clue in this case is if coolant is leaking into an oil passage, the oil level will go up and it will start to look like a chocolate milk shake. If you have to add oil too, you can't use the level as a clue either. These guides can help.

https://www.2carpros.com/articles/car-is-leaking-coolant

and

https://www.2carpros.com/articles/head-gasket-blown-test

If you see water droplets under the oil cap along with that white substance, it is more likely it's from condensation due to excessive short trips. The engine needs to get up to normal temperature for an extended period of time to vaporize that water and draw it off. Sludge will also form in the oil when the engine is run too much at below-normal temperature. A 30-mile trip at least once a week should reduce the amount of condensation in the oil.

It's natural to smell engine coolant when you have a leak. On Fords, a common cause is rusted-out metal pipes that are very thin to start with. If you can't tell where the leak is because everything in the area is wet, you can wash it off, then add a small bottle of dark purple dye to the coolant. Later you search with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. Auto parts stores have the dye, and many that rent or borrow tools will have the black light.