1. WET AREA :: (T-TD less than 3*C)
The temperature dew point spread is less than 3ºC so the relative humidity is quite high.
2. Areas on the chart that show grid lines.
Not quite sure what you are referring to but lat/long and territorial boundaries are depicted.
3. Where temps are indicated but in some cases it appears that the Dew Point is higher than the Temp. This I don't understand.
Clearly the dew point cannot be higher than the temp. I think what you are looking at is the reported temperature/dew point spread as opposed to the dew point temperature. ie you may see 05 [upper left of symbol] and 6 [lower left], where 05 is the temp and 6 is the spread (not the dew point temp).