ISSA is actually a decent cert. I like them, NSCA, NASM. I'm NFPT, and I like it too, but keep in mind that the cert is just the beginning. As you have done in this forum, you have to continue to learn, and eventually who you're certified with will become irrelavent.
I can say that I don't recommend ACSM after attending the last two of their big summits. You being an oly lifter would clash with their philosophy, which seems heavily in favor of avoiding loaded lumbar exercises at all costs. I wonder how many clients of ACSM trainers end up with bad backs from being careful to never load the lumbar muscles.
When you get ready to sit down and talk about opening a gym, let me know. You could say I have a little experience in that area.
Congrats on figuring out what you want to do. It is pretty gratifying when you finally give in to your calling. Despite the challenges that face you, when you follow your bliss it truly is the path of least resistance. It has been a wonderful and rewarding career for me.