"One question I've always had about IBL is does it matter which direction the three arrows within the circle are pointing? I usually point the arrows facing the figure."

Nope.  In Poser, with IBL, it doesnt matter.

"I also had to ask because of money reasons. I've heard that Lux/Reality 3 does take awhile to render."

That's an understatement.  Luxrender is a physically accurate, complex lighting render engine, but it's not optimized for speed.  Even with GPU accelleration, it's a very poor performer.  It will take hours or days to render a scene, but the results, if done right, can be as realistic as a photograph.  I've seen Luxrender renders that were indistinguishable from reality.  I've only seen a handful of the best Poser renders that I could say that about, and most of those had a lot of postwork done in Photoshop to make it so.  You can achieve photorealism in Luxrender without as much postwork.  I've read articles about how "unbiased", physically accurate render engines are cutting down on the amount of post production studios are having to do to achieve film-quality results, so that's saying something.  Of course, most of those studios aren't using Luxrender, but Arnold and other unbiased physical render engines in their pipelines.

I don't think you've achieved the full capacity of what is possible in Firefly, just judging by your statements in this thread.  So I think it would be wise to save your money at this point.  The time you'd save in setting up a scene for photorealistic results (if any) will be lost in render time.

If you want much faster render results, but still achieve photorealistic light, like in Luxrender, then it's going to cost a lot of money.  You'd need to invest in a higher end Nvidia graphics card, and possibly something like the Octane render engine.  It won't be a cheap solution, unless you already have a good Nvidia card, but it's actually faster than Firefly, and as good as Luxrender.  For now, I would suggest testing Luxrender out yourself with some sample renders on your machine, as there is also a free exporter for it that's ok for testing the engine with Poser.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.