Devv

Tam recommended the Triton v2 to me, but the seller I wanted to use did not have the coils I wanted for it.  They did have a Triton Mini with Clapton 1.8 ohm coils.  Wow, this little tank is a beast.  Super clean vape, great tank and built extremely well.  Its my go-to morning vape since I have a coffee juice in it (Cyber Cafe Royale).  No spitback, gurgling at all.  One of my next purchases will be a v2 tank though.

With all those tanks I hope you're buying more than one iStick 50W or at least another mod/battery for a back up.

If the 3 mg of nic is working for you, then I wouldn't change a thing. If it's not quite doing it for you, go up a little. Personally, I started with 24 mg of nic in my juice to get me off cigarettes, but that was with a whole different set up. The tanks and coils these days are much different from back then so a lower amount may work just as well. You want to be watching the PG/VG levels of your juice, though. Too much VG and the juice will be too thick for the wick to properly absorb so you may get dry hits, which are not pleasant. Most people go with a 40 PG/60 VG or 30 PG/70 VG. I wouldn't go much higher on the VG than 70% or it would be too thick.

We stress getting back ups because you never know what will happen. What if you drop it and the battery no longer works? Do you want to wait a few days for another one to come in the mail? What happens if the battery just stops working for no reason? That can also happen. Even though they say you can vape while the iStick is charging, I wouldn't recommend doing that. So, when it's charging, what are you going to use? Getting back ups and back ups of back ups (in case of multiple failures -- it's happened to most of us on this forum), is always a good idea.

There are industry standards that most manufacturers follow that essentially allow you to marry any tank with any mod. There are a few exceptions but even those have adapters that you can use. Everything you have listed is compatible.  The only thing you are going to run in to is slight variations in performance that may not amount to much at all.  And then there's the learning curve where you learn what your preferences are, what you like and dislike about a mod or a tank. This will change over time too.  Have fun exploring. And don't forget to pay forward anything that doesn't suit you. A little good karma never hurt a vaper. 

Those are very dangerous words to utter here. 
First, let me ask you some questions, then, we can get on to spending your money recommending equipment for you.  
Do you want a kit or go a la carte?
Do you want a variable voltage/variable wattage device and/or TC (temperature control)?
Do you have a preference for something that has the battery integrated into the unit or one where you can take the batteries out (this would require an additional purchase of a battery charger and batteries).
How do you vape? Are you mouth to lung (like smoking a cigarette where you draw the vapor into your mouth first before inhaling) or direct lung (where you inhale directly into your lungs)? This is so we can better recommend the right style of tank for you.
That will do for a start. Other questions will come later as we further fine tune the recommendations.