Mark - I suspect that Remco is referring to the fact that you are mixing flashes that are daylight balanced and "hot lights"' they will have different colour temperatures and will give you real and unsolvable mixed light issues. Secondly, the light output will be so low, that you will find that they don't add any value to your shots.
That being said, based on your purchase plans, it is fairly clear to me that you don't quite get studio lighting concepts. Like camera lenses, each light in a lighting setup has a specific purpose and you should learn what a single light source wll do before you start blasting away with multiple light sources. You should also understand what an umbrella or softbox do and cannot do for you before you run out an try to set up a multiple light setup. You need to understand lighting ratios and what they do for an image, etc.
You need to understand some of the classical lighting setups an how you will use them. By the way, in their basic form, need a single light source and a light modifier, not a hodge podge of different light sources blasting light through your garage in an uncontrolled manner.
At a minimum, you will need a key or main light. That will light up your subject. You will also need a fill light to manage the shadows in your subject's face, especially for the eyes. You don't actually need an active light for that, but rather a plain while piece of foamcore or coreplast plastic, but you could go for one of the fancier commercial reflectors, they are pretty inexpensive too. A lightstand and clamp work well to hold it, but an assistant is easier to use.
After this two-point lighting, you could introduce either a hair light (to help separate the subject's hair from the background). None of the equipment on your purchase list will work for this as you need something like a grid spot to give you a focused light. A kicker or back light can be used to separate the body from the background in a similar fashion to what a hair light does, but this light always comes from the back. This is three-point lighting. Add another grid spot to illuminate your background, and you have four-point lighting, as you have introduced another element to separate your subect from the background.
If you are truly looking at a studio, I would suggest the monolight route. It will give you a lot more flexibility than what you can accomplish with a couple of battery powered off-camera flashes. The light output and control are far better with studio lights, and you can get many more types of light modifiers for them.