Ram is there to be used not to be free. so it's not a problem don't worry. it keeps some apps in ram so when you open it it opens fast.
And I recommend you not to use ram cleaner apps. when there's not enough ram LMK will kill some apps so don't worry about ram,
About battery life, yeah it sucks after MJ7 update. I think they fixed it in ML1 update. if you don't want to install custom roms wait till you get the update.
But now I'm on CRISKELO-Rom NOTE III-N900 V05 + halaszk-UNIVERSAL5420 kernel and my battery is good.
also, CRISKELO-Rom is optimized and have more free memory, the developer removed some bloatwares.