What you need is for the cells in the berries to be able to release their fruity goodness and sugars. Freezing accomplishes this (as would crushing and possibly adding sugar), and you can get berries from the store like that ready to use. Now, if you were inclined to get really fresh about it, this *is* strawberry season in some places (like here) so you could pick 'em in the morning and brew with 'em in the afternoon.
There is a (small) chance you'll get an infection from the berries...either pour hot wort over them (normally a terrible thing to do), or hit 'em with some campden tablets the day before you add them to the wort/beer, or take your chances. I made a strawberry mead and didn't do anything, and it came out fine.
Typically fruit is added to the secondary so you don't lose the fruit aroma, but if the recipe calls to add in the primary, go for it. Depending on how much strawberry you add, you may or may not see the color change...the mead (15# honey, 12# frozen berries) came out a nice orangey color after aging (although it was mighty pink out of the primary).