I personally prefer the ~$6 evod to the $20+ protank; good airflow, easily findable coils, cheap and comes in cool colors or stainless steel. When I first tried the protank, I hated it and got odd flavor from it as well. What I learned is that you have to take advantage of it being disassemblable and clean it very well with soap and hot water, and rinse it well and let it dry. After I did that, the flavor was much improved. I still prefer my evods though, super easy and in my opinion, the ideal airflow.
I agree with this and if you want a good, solid step up from there, the Kanger MINI pro-tank v2 is a an even better choice in my opinion. The actual protank (larger of the two) is a lot more fussy to deal with, it's not an "out of box perfection" type thing. The mini is my daily go-to and I'm into all sorts of stuff in the vaping world.
Some tips? Make sure you're priming your wick. Dab a bit on the wicks and then fill your tank...it'll help get the juices going. You can also try sucking on the e-cig without hitting the fire button, that'll do the same thing and is a good thing to do once or twice if you start to "sense" your wick running dry. As was mentioned, some juices gunk your coils up...some faster than others. (Can be a day, a week...maybe a couple at most.) I prefer a juice that does it less myself and that's a quality I generally look for in a liquid. You can clean them...let 'em sit in Vodka or (better yet) Everclear overnight and then dry them out. Many of us get into rebuilding, too, for new coil's to be cheap...but that's probably more than you want to think about right now.
As for variable voltage...the resistance of the coil (the thing that heats up and vaporizes the liquid) has a significant impact. I don't want to bore you with the technical details, but essentially, VV allows you to tweak the vapor for taste, regardless of the coil's resistance. This action can have a dramatic impact on the taste, the amount of vapor you get and the temperature of the vape you get. It sounds to me like you probably have a low resistance coil.
Hope you get things figured out. It's not hard, but there's definitely more to it than smoking. Be patient with it and you'll find the right thing. Once you do, vaping will become easy...and maybe even enjoyable. Good luck!
Edit: Just read your last post, sorry. Some juices just suck. I mean...reallly...really suck. I had at least four from my B&M and it took me awhile to figure out it was just terrible. It's some online vendors too, but many are good/great. Read the juice reviews in the e-liquid forum, there's also two forums dedicated to juice reviews for recommendations.