OK, although probably not a question for this thread - it still feels as if it pertains to this thread. I assume a handheld lightmeter would help? I mean from what I understand, I would hold the meter where the subject would be and it reads out the several combinations of required shutter/ f.stop/iso to get a proper exposure right?
How does that work in terms of it assuming the amount of light that will be provided by the lighting setup?
You need a lightmeter designed for flash.
And as I said earlier - shutter speed shouldn't be considered a variable when shooting flash. You should stick to the x sync speed, there are exceptions to this, but it'll not help you to learn about them before you've got your head round the necessary knowledge.