Originally Posted by jms698 
What is the difference between a color gel in the flash slot and a color temperature gel to cover the flash head? I can understand the latter is to modify the color temperature of the light coming from the flash, but what does the former do?
As for diffusers: are they really necessary? Do you only need a diffuser if you are taking a picture with a wider lens than the flash range covers, or do diffusers have other uses?
Sorry for the confusion: they both go in the Vivitar slot. In your case, they'd also go in front of the beam.
the difference is very subtle: I use color gels ONLY for color effects (though they could possibly also change the temperature) like changing backgrounds colors.
Now the temperature filters, are for when you KNOW you need to adjust for temperature, in this case you need specific filters for the occasion. usually they are used for the main subject.
They are the SAME visually, and are mounted the same way.
Regarding the wide diffuser, best thing for you to do: experiment with your 360.
