It sounds like you're expecting the model(s) to make the difference, going by the road map you've laid out. At best, the model is the final couple of percentage points. There are some differences a model will make to your photography, but that's mostly about taking proper advantage of facial structure and so forth in your lighting. You don't need a certified "model" for that, just people with different face shapes.

Ninety percent of the job is understanding light, and how the quality, direction and contrast interact with the elements in the photograph. In this case, you need to understand how lighting works primarily with skin and fabric. Now, it may be somewhat easier to convince someone you've rented to put up with your experiments than to corral friends and family for the job, but that's really the only advantage to getting a "proper model" during the learning phase. Direction is still going to be difficult, and it's still going to be your responsibility. (And you're still going to have to learn how to pose yourself and how not to be embarrassed when you demonstrate to your model what you want.) But at this point, it's all about learning. Learning how the light affects colour and contrast, how it works with the planes of the face and body. Light is your main tool; cameras, props and so on are secondary. If you want to fulfill your creativity, you need to be able to design the photograph in your mind before you take it, and that means being able to predict the effects of light.

Everything follows from light. It doesn't matter if you have the right model with the right look in the perfect costume with impeccable makeup and hair, if the light fails, the photograph fails. If you don't know light, then constructing the picture you've seen in your mind's eye is going to be a real SOB. So your mysterious steps 5 and 6 are actually intermixed with steps 1 to 4, and there's no way to do Step 1 without including Steps 2, 3 and 4 (unless you mean "Learn how to use the flash" in the sense of "I've read the manual and know what the switches and knobs do").

There's nothing in Ben's portfolio that can't be done with somebody hired (for money or TFP) from ModelMayhem, or with a cooperative friend (or friend's kid, or a barista on her day off, or...). It is all about experimentation and practice. Hours and hours and hours of obsessive practice, paying more attention to your mistakes (and learning from them) than your triumphs. Sure, some of the shots require more "production" than others, but if you're involved in a photography group you can all play assistant/grip to each other in turns. That way you all learn. And eventually you'll hit a point where you're going to have to involve stylists — hair and makeup people who know how to translate your vision into reality; clothing and props people who know where to find what you're looking for — but you can go an awful long way with slightly funky people before you get to that point.

What it all boils down to is shoot. A lot. There are no short cuts. There is no "secret sauce". Shoot until you know what you're doing and, when that gets stale, change what you're doing and shoot until you understand that. It takes a lot of work, but a lot of work is what it takes.