Nutrition is poorly understood, but we do know that seed oils have a different profile than what people used to eat, and their high omega-6 fraction promotes inflammation. On the bright side there seems to be a reduction in heart disease (with some of them like olive oil) from their polyunsaturated fatty acids, which however doesn't improve all-cause mortality.

http://wholehealthsource.blogspot.com/2011/08/seed-oils-and-... gets into a little of the picture.

Personally I take a flaxseed oil supplement (for high omega-3), often fry in olive oil, and try to minimize seed oils otherwise. (I don't try that hard, but my intake has changed since learning about this.)

Salt intake I wouldn't worry about unless you have a specific issue making it a problem.

Disclaimer: layperson.