Echo above with one caveat.
Wife has Macbook, I an iMac both from 2009. Both going strong. We've got Office for Mac on both, but it isn't really that good. We use Apple's free Pages programme which, although not a clone of office, it does everything we need. Apple also provides free spreadsheet and presentation software. All of which can write files in MS format.
On memory the rule of thumb for any PC is to get as much as you can or afford. But Apple's extra memory is expensive and not good value for money. But adding memory to most Macs is a doddle. I've upgraded both our machines to maximum using chips from thes guys :
Other World Computing (OWC) - Performance Upgrades For Your Mac. (Satisfied customer speaking, no other relationship with company) Their website has videos showing how to install the chips, so you can decide in advance if it's something you want to do.
MS Word etc, is available for the iPad, but it's a subscription product.