I drove my Honda off the lot straight to a Krown applicator. I don't like it- too low viscosity and if you get it on rubber it swells it (I think they all do this) they slathered it all over the engine bay. I use a spray on product that gells up and has graphite so you see easily where it is applied.
Down here in Kentucky it's rare to even see a salt truck anymore. We haven't had hardly any snow now for many years and don't have to worry about rust anymore.
1) you want a product that creeps. It will tend to creep over an area should a rock scrape some off.
2) NH Coatings sells a brush on product in addition to spray on products. The brush on is for areas where road spray might wash off a sprayed on product.