Here, a 0.25 dp is standard, while 0.28 dp is standard on a shadow-mask monitor. They can't be compared, then, by dot pitch alone. The motto here is not to pay too much attention to dot pitch when considering your next monitor. These two features are discussed together because neither can really be discussed alone. Each depends on the other.
Refresh rate is the vertical frequency, or the rate at which each pixel on a screen is re-drawn.
A low refresh rate result in an image that flickers, resulting in eye-strain. Due to limits in bandwidth, the rate at which the screen is redrawn decreases as the resolution increases. Bandwidth is the rate at which the monitor receives data from the video card. To find out how much bandwidth is needed at a particular setting, simply multiply the horizontal resolution by the vertical resolution by the refresh rate. For example, a refresh rate of 85Hz at 800x600 resolution would require 40.8 MHz bandwidth.