Cartos can get hot if somewhat low resistance for the battery (desired by many) and especially if dragged long. IMO the model may be too weak for you and may not put out enough vapor fast enough to satisfy you. And it's like the super-mini of carto units, a Chinese wholesaler model sold by ripoff rebranders at a higher price. The kind of ecig most people will get annoyed with within a month.
Get a decent supported 2-piece model if you want 2-piece. If you have a hot carto you can put a plastic or delrin drip tip on it as a mouth piece. Look at KR808D-1 aka Vapor4Life in colors (and most prefilled cartos are there - nice soft-cap ones you can add juice to and keep using for days). I recommend a plastic or delrin drip tip - not to drip in - just as a mouthpiece if you want to take big drags and it's a hot carto - LiteCigUSA.net has both delrin and plastic 510/901/KR808D-1 ones and their shipping is cheap. Both Vapor4Life and LiteCigUSA have blank soft-cap cartos. (at LiteCig see the standard resistance - not LR which are for fat battery models - Premium KR808D-1 cartomizers)
That is your absolute bet for prefilled cartos on a well-supported model in the normal-price marketplace.
Basic white or steel KR808D-1
LiteCigUSA.net
VaporLeaf.com
Colored kits/parts and the most prefilled cartos (has eliquid too)
Vapor4Life.com
I recommend manual batteries. Most people here use manual ones. They are safer from death-by-juice leak because they are not dependent on a drag sensor in the threaded end. And manuals won't turn on by accident from wind or vibration. I also think they are less work.
And if you are interested in fat battery 2-piece models with 6-8+ hour battery life, see CigEasy's Elegant Easy and leCig's PigCig.
PG - thin, lets through the most of nicotine's harshness and TH, the most flavor, has less vapor
VG - thick, smooths the harshness and TH, dulls the flavor a bit, has more visible persistent vapor
I vape neither 100% PG nor 100% VG (except my first bottle I bought with my kit was 100% PG). It's usually Dekang juice from China. I prefer blends. I like anything within 10% of 70pg/30vg which is a popular ratio. A few juices I have are smoother and 50/50.
If you get a Riva 510 instead, most cartos will be blanks. It will come by default with atty and carts. You can buy and use cartos on it - you may need to remove the cone or use a 510 extender to get the carto to stick above the cone. There are fewer prefilled cartos for 510 threading but probably a larger variety of blanks. And Riva can use both the cooler standard resistance blanks and the hotter low resistance ones for 510. To use prefilled KR808D-1 cartomizer like the Vapor4Life ones, you would need a 510 to 808 adapter.