Hi Guppstah, welcome aboard. For your upgrade I would suggest a couple of iClear 16s [closest to your existing CE4] and maybe an Evod or a mini Protank. The iClear 16 would allow you to find out if you prefer a warmer top coil vape which you have now or a cooler bottom coil vape which you would get with the Evod or Protank.
I am assuming you already have a 650 mAh battery and a charger, so you wouldn't need to buy a starter kit.
Batteries - I am assuming your current battery is a standard 650 mAh ego battery. Does this last all day, or do you need a bigger capacity battery, say maybe a 1000 mAh? mAh is essentially a measure of how long the battery will last, not how much power it will produce in terms of heating a coil. Standard ego type batteries will all output at 3.7 volts [or thereabouts] regardless of whether they are 650, 1000, 0r 1300mAh. So, if your battery lasts all day just get another 650 mAh for now, but if you want a battery to last longer, go for a 1000 mAh or even a 1300 mAh, but remember that the bigger the capacity a battery has, the bigger it will be, so may impact on your requirement for it to be portable. Whatever you go for, get at least a couple so you're not relying on one battery all the time. You could also get a spinner and go variable voltage, but that is maybe for another day once you have consolidated.