Op - please please please don't try and do any modifications right off the bat. Don't try and change it to mavericks, or use older apps. You're going to create unnecessary problems for yourself.
Load yosemite, and run all the updates/current apps.
Try that for awhile.
And reading the prior posts - you were using activity monitor wrong. What you're looking for is the green graph labeled "memory pressure." As long as it's green - you're good on RAM use!
It will raise and change color if it becomes overwhelmed - so that's what you're looking for.
Safari is NOT inefficient or a memory hog. You want memory to be used, and apps using it, are what they're suppose to do.
Currently, I have Yosemite on an 11" 2014 air, a 2012 Mac Mini, a 13" 2014 rMBP, and had it on my 15" 2012 cMBP.
I have zero problems with it now, and if you have an iPhone, being able to answer calls/texts from it has been great. I just leave my phone plugged in now, and can make calls/answer from any of my devices..
If you want portability, I think the 13" retina is what you should of got (the 2014, which is on sale at Best Buy if you're in the US). Maybe an Apple TV for screen mirroring on the TV if you're going to sometimes want it on the TV, or track down a cheap mac mini (I have my 2012 connected to my HDTV for movies/tv, works great). You could then add a portable hard drive to the mini, and set up sharing between the retina so you can access stored files anywhere. You could even control the mini through the retina via screen sharing and use it as a remote control of sorts...
Anyway, just a thought.