zilla, I've got to compliment you on asking all of the right questions beforehand rather than rushing into things, you're definitely doing it the right way
I can't comment on the fish too much because my experience is almost completely with African cichlids. I agree with Malkore that Yellow Labs and Ps. acei will get along better than most Africans in a mixed community environment, but like Mattrox said, make sure your water conditions work for all of your fish.
As to the substrate mix (Eco-Complete and Flourite) I've got some of both mixed in my tank right now and the Flourite does tone down the black of the EC somewhat, although my substrate is almost completely covered as it is and I rarely see it
Your plant selection looks great for a medium light tank. I didn't catch if you were using
CO2? I can highly recommend it. It helps make things so much easier as far as dealing with algae and keeping your plants healthy, but isn't necessary unless you go above 2
wpg and want to raise certain species of plants that require it.
I'm anxious to see this tank come together