I have been using photoshop for quite some time and, ever since I bought CS, I have had some troubles with it.
1. Every time i fill in the dotted areas made by a select tool, there are always blurry edges that extend beyond the boundaries of the selection. Whether it be with a brush, gradient, or paint bucket fill, there is always a hazy edge to it.
2. Sometimes, when I brush in a new layer, the fill is not complete; little tiny pixels break through and will not change color unless I use the polygonal lasso tool, select the stubborn area, and fill over it on a new layer. Keep in mind that brushing over a new layer does not completely cover it; that is the problem.

So, with that said, what can I do to fix these problems?

Thanks in advance!