I think we'd better clarify quite what you're asking - the other products you've tried, what was disappointing about them, exactly? Were they combination formulas, such as weed, feed and mosskiller, or just lawn food?

Both soluble and liquid feeds need to be applied frequently, since they wash out of the soil as quickly as they washed in. For the same reasons, heavy rainfall will reduce their effectiveness. If that is the problem, you might want to switch to a granular feed, preferably an organic one.

But if you do, make very sure to apply it very evenly or you can finbsish up with burnt patches. been there, done that.

Oh, yes, that's true of any fertilizer! Hand sowing is possible, but takes a fair amount of skill--it is much better to use a spreader of some sort.