I, too, am a first time Mac(book Pro) user and purchased the same model as you a few weeks ago. I upgraded to the same 8gb of Crucial RAM (first time doing this) and it was really pretty simple. Just pop off the bottom panel, replace with RAM sticks, and screw panel back on.
If you are using Photoshop and editing video it could definitely pay off while you are doing those. You will have a more snappy experience while opening/using other apps along with those programs running. Also, just running multiple programs (Office, Safari, Mail, etc, etc) will be quicker. I also read somewhere that w/ 8gb and 16gb of ram, some of the RAM dedicates itself to graphics processing. Note that this does not mean that you will have dedicated video RAM, but I guess it helps process that stuff (sorry, I don't know too much about it).
Make sure you have a decent 00 or 01 philips head screwdriver. I used a crappy one and it pretty much stripped two of the screws used to hold the bottom panel on. Not a big deal, but the two screws aren't totally flush with my bottom panel now. Will probably get new screws to replace them when I have a chance.
Good luck! It's a fun & easy upgrade and doesn't cost too much, either, for some extra power.