Kibes,
Dont be overwhelmed......carto tanks are EASY!!!! Thats the beauty in them!!! Choosing one that matches your style is the only hard part!! LOL

Go straight to a pyrex glass tank, skip the plastic tanks (if cost is not an issue)!!
You have already been directed in the right direction with Phiniac, IBtanked and Valley View Vapes. I own a few of each of those brands and LOVE every one of them!!! Up grade to the stainless steel caps when you can

As far as cartos go I have used all the popular brands and have had good and bad experience with all of them......when it comes to "how long does a carto last", it is luck of the draw (as previously stated). I have had some last a few days and others last a few months!!! What ever!!! I personally like the Punched cartos from iKenVape!!! The produce tremedous vapor with EXCELLENT FLAVOR. Hands down the best cartos on the market today, IMO of course.

But thay are often out of stock, and sell out quickly when they are in (that should tell you something)!!!! BADitude buys them all up, LOL

Cartos come in STD (standard length) for shorter tanks and XL (xtra large/long) for the taller tanks. Most sites will tell you what size cartos will fit the tank. Ohms is a personal preference......what voltage do you like to vape at? usually LR (low resistance) cartos are good up to 4V and STD (standard resistance) are good for 4-5.5V give or take alittle. There is a Vaping power chart posted some where on this forum that is a good guide to use (i'll see if I can find it and post a link to it, soon).
Carto tanks are great, easy to set up, easy to fill, low maintanence, easy to clean and essentially leak proof!!!
Spend a few bucks and get yourself the tank filling tool, makes filling the tanks alittle easier......but the really make sliding your carto into the tanks easy and extends the life of the O rings on the inside of the caps!!
Good Luck and Happy Vaping!!!