Clarification on the process for making fudge
I like Kristina's suggestion that you research some of the basics of candy making. I'll answer those questions only briefly.

Generic Candy Questions 


You don't need to heat particularly slowly
This is not like an egg custard where the speed of heating will affect the curdling temperature. You're just trying to get water out. Just don't heat it so fast that you burn the bottom or overshoot the target temp.
Temperature range
The different candy stages have about a 10F range. 2-5 degrees isn't going to make much of a difference but 7-12 will start to.
Adding volatile flavorings to candy
Many flavorings are lost to heat. Such flavorings are added at the end because if they boiled the entire time they would be gone.


Fudgy questions  


Stirring
Stirring isn't required. The syrup won't burn unless you have the heat too high and are using a very cheap pot. Additionally, the syrup absolutely should not be stirred in the final moments of boiling because a sugar crystal might fall in that doesn't get dissolved. During cooling stirring would destroy the fudge because it would all crystallize.
Drying out
This is not a problem. The fudge will not dry out in the time it takes to cool.
Losing the gloss
As I wrote in the other answer, the syrup is concentrated and then cooled to a super saturated state and not allowed to crystallize. When it has cooled sufficiently it is mixed like crazy to form your crystals all at once. When this happens the shiny, glossy syrup suddenly fills with crystals and becomes thick and loses the gloss. 

It is important that the syrup be cooled enough that it is ready to crystallize at the drop of a hat. Again- if you stir it early, as it cools, you will end up with rock candy (more or less). I just leave my candy thermometer clipped on until the target temperature is reached. Make sure the thermometer is clean- one stray sugar crystal can ruin the batch.