Assuming you're running Yosemite or Mavericks (which you should be -- BTW I have the same model of MBP that you do, it has lasted me 3+ years of solid service -- upgrading the RAM to 16GB makes it pretty awesome, but I still haven't moved to an SSD yet) you don't really have to shut down apps. The OS takes care of memory management pretty well -- it compresses RAM, it keeps closed programs in memory if it's able to, and it will shut down unused programs if it needs to clear up some memory ( see
http://arstechnica.com/apple/2013/10/os-x-10-9/17/ and
http://arstechnica.com/apple/2011/07/mac-os-x-10-7/8/ -- John Siracusa's reviews of OSX are pretty much required reading for serious OSX users, there are really a ton of interesting features behind the scenes). And especially if you have tons of RAM like I do, then there's hardly a need to shut down commonly used things.
I pretty much leave Excel, Firefox, Safari, Word, Calendar, Console, iTunes, and Preview open all the time. Rebooting pretty much only happens when there's an OS update requiring a restart. When I reboot, these all come back up with the same stuff open as when I rebooted it. I take my laptop with me all the time, and all I have to do is shut the lid.... I can't think of the last time I actually "Shut Down" my MBP and left it off. The Mac world is a lot simpler than the Windows world. Stuff that *should* work in Windows but often doesn't (at least enough to make you nervous), *usually* works on a Mac.
But yeah, there's really no need to quit apps. For apps that I don't use often, I will go ahead and quit them to get them out of the Dock, but for everything I use regularly.... nah. (But Firefox does have memory leaks and other problems -- I have AdBlock and several other plugins installed that might be the actual cause, and I regularly have several hundred tabs open at once so who knows -- in any case, I do find that it starts to slow down over time, so I tend to Cmd-Q Quit and then restart FF once or twice a week.)