Hi, Welcome to ECF & congratulations to both you & your Mom! I've never used a KR808 but have read good things about them by some very knowledgeable folks on here. I think the #1 most important thing that will determine if it's a "good PV" is, "will it be used?" No matter how much it costs or how many bells & whistles it's got, if it winds up in a drawer under a full ashtray, a pack of smokes & a lighter then it's not a very good PV *for that person*. I think your Mom made an excellent choice.
As to the cartos for your eGo, I'd suggest Boge LR (2.0 Ohm) for a nice, warm vapor. I also like the Smoktech XL single coil 1.7 Ohm, also low resistance and hold almost twice as much juice as the Boge. If you prefer a cooler vapor you can use a higher resistance carto, such as a 2.5 or 3.0 Ohm.
I've never used an eGo so I don't know if you can direct-drip on your atomizers (I'm sure somebody on here can tell you) but for trying out new juices, direct dripping is the way to go. For that you need a dripping atomizer about the same resistance as the cartos you'll be using and a drip tip. The attys are pretty easy to flush out between flavors, so you can test juices before filling a carto with them. Here's a good site for the cartos: 
Crystal Clear Vaping and they have *free shipping!* (which is ground, but still cool). BTW, I strongly advise you to avoid dual coil cartos on your eGo; without going into the electronics involved, your battery doesn't provide the voltage needed to get much service out of them. I know, lots of folks swear by 'em but I've tried them at 3.7 volts & they need quite a bit more voltage to cook like they should.
Blessings to you both, & Happy Vaping!   
