A few things...
If you're new to dripping and rebuilding then a dedicated dual-coil setup might be frustrating to learn on. My honest suggestion would be to get an EHPro Atomic clone to start your rebuildable experience with. They can be found all over the place for a low price. As well, it's a three-post setup with a small chamber and the option to use dual or single airholes of different sizes. In other words, you can single coil it as you're learning and still get excellent flavor, but you can open the other airhole up and pop in a dual coil build when you're up to the task and ready to blast yourself with vapor.
As I said, it's a smaller RDA (19mm diameter), so it might look strange to you if you really like rdas that are exactly as wide as the mod they're on, but that also forces you to learn to build small and tidy setups (which is a good skill to have). Perfect beginner's rda, imho.
As for your mod, I too would point you in the direction of a more powerful variable device before a mech, but that's just cause they're so easy. Newer devices can fire muuuch lower resistances than your mvp, so a mech isn't necessary any more to have fun with rdas and it makes learning to build a lot easier since you can wrap a crap-ish coil and immediately see that it's not the resistance you were shooting for... but then just crank it up or down to accommodate and vape anyway. There's a ton of stuff out that fits the bill, so I'll just say happy hunting (though I do love my Sigelei 50w box, and I think they just announced the 50+...).