Well looks like you have all kinds of good answers.. so here is what I will offer you.
Confidence
Yep, that simple. We sometimes get to be over technical. Everyone has a personal preference. It does not matter what you end up using, how you end up using it or if you tell us all to stick our heads in the sand. What matters is that you are not smoking.
An ecig device is a fairly simple concept. It can become exponentially complex, but that is just added layers. All you need to know is that you heat up a liquid that vaporizes and that gives you flavor and nicotine.
I broke apart one of my Kanger protanks for you so some of the complexity and fear can be reduced.
I took the bottom off and drained the liquid... yes liquid does darken in a tank. Some darken faster. If it gets to looking like slug you can add fresh or clean it out. I like to just add fresh. Matter of personal preference or what works best.
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I removed the coil assembly
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This is the cap that helps keep juice from getting into your air pathway. When you put it all back together don't pull it down fully. Let it sit up just a bit..maybe a milimeter. This way the tank will seal it down when you screw it all back together. Here is a pick with it almost removed.
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Taking the shaft off the coil will require some strength or pliers ( just be careful not to hurt yourself). It is simply press fitted in place.
The actual coil is under a small piece of wick. This is called a flavor wick and its job it to help stuff the side holes where the juice flows in and to slow down speed of the juice to prevent juice from "popping" all the way up the tank into the drip tip. Sometimes these can be a reason a tank does not get the juice in fast enough. That is another debate... it is what it is.
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And that my friend is what it looks like. The coil has one end going to the positive end of the battery connector and the other into the negative. While I don't recommend it, you could just take the coil out and attach it to a battery and it would heat up. The wick it just to bring juice to the coil. You could drip juice directly onto the coil for the same effect.. but that is not very efficient. Here is what this looks like heated up
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In the end it is just like a light bulb... instead of visible light it gives off heat.
The variables that can come into play and that confuse people is all about how to light it up. Things like wire size, wire type, wire length, wick type, wick length, wick size... etc
Do not worry about it. Take your time and learn. Take the advice and see if you can get your device working. Eventually you can play with other ideas if you want to.
I wish you luck and welcome to our insane community of great people!