Pricing
okay Shops will never be able to beat online prices. its just not possible when your buying online you can buy straight from china there's no way a shop can compete with that. but when buying from a shop and paying a little more you are also 1. not paying for shipping 2. not having to wait for your item in the mail 3. supporting a local vape shop

always a good thing. But you bet if theres a big price difference im buying online for sure and shops may not have everything you want either most people i think dont even have a shop near them, im not trying to discourage online shopping at all =P just saying after paying for shipping and then waiting for the item if the shop has decent prices it would have been worth it to ger it from the shop lol. Moving on
Terminology
This one gets every new person there's loads of it, but u seem to be focused on Juice Delivery Systems. ill go over the main 3.
Cartomizors/Carto tank: if you have ever takin apart whats inside of a cig-a-like cartage you will see this cotton ball like stuff that holds juice and lets it drip down onto an atomizer. so a cartomizor id that system with a hole or 2 punched in the side then put into the center of a tank so the juice can slowly be fed in to keep that cotton ball material on the inside saturated.
Clearomizors/Glassomizors: clearomizor is plastic, glassomizor is glass. how they work is theres a coil wrapped around a wick and the coil will sit at either the top or the bottom of the tank and juice will be fed to the coil from the tank through the wick.
RBA (rebuildable [dripping] atomizer) : not for the faint of heart these require you to build you own wick and coil to use them but i will explain them just so u have a better grasp on everything. an RBA is simply a wick and coil that you have made yourself and it sits in a dome and you drip a few drops of your juice right into the wick/coil and vape it a few times and then drip some more then vape then drip vape drip vape.
the one i would like to have you set up with is the EVOD which is a clearomizor and the most simplistic while still having a great vape.
as for the battery when u say you got the smaller EGO im thinking u got the 650mah (milli amp hours) which is how battery life is measured. the EGO twist or the Vision Spinner i am recommending to you are 1100mah - 1300mah so they will last 2x as long also you may notice these are more expensive then normal ego batteries that's because the bottom of the battery is actually a dial where you can turn your voltage up and down which is an awesome feature to have and worth every extra penny. It will allow you to adjust your vape, not getting enough vapor or enough taste out of your juice turn up your voltage! if your juice is tasting burnt or hot turn down your voltage! lol.
im just going to repost the things i suggested for you here.
1 EGO Twist Battery + charger *OR* Vission Spinner Battery (they are the same thing)
1 EVOD tank "clearomizor" (Kanger Protank if u wanna spend a little more)
+ american made juice.
If you have ANY questions on any of this stuff ask, seriously i like helping.
even if u want me to go find this stuff at a good price for you and post some links i will haha just ask.