Based on what you said you're looking for, yes i would say the m40x would fit that bill. 1/2/3 is just battery size (and life), with the 2/3 being in the super-mini range. The 402 is a nice balance between battery life and mimic'ing an analog (its a few mm shorter in length than a 100 and the same width). The biggest downside to this model (imo) is the cart liquid capacity, 0.3 ml for the standard carts and 0.4 ml for the XL carts.
I would also encourage you to check out the VaporKing site and its line or KR808D ecig before making a final decision. I think there's a charging case available for that model too. You can find KR808 gear at many other retailers too. And the cart capacity for that 2 piece model is 1ml. A couple of posts back, Mister who has tried a variety of models, put in a really good word for that one.
Truth be told, the KR808D is the model I'm recommending to a friend of mine to start out with. Mostly a matter of the convenience factor (in theory since i haven't actually tried it yet). Good performance with greater convenience. I'm not sure what the batt life is like for that model, but like the 401/2/3, there are different sizes avail for this model too.
Welcome to vaping and all the bewildering options... just wait till you get to figuring out what liquids to vape once you've decided on the devices to vape with
