I see a few questions in your post, so i'll try and address them to the best of my knowledge.
1. Currently, the most popular of the hardy apistos from what i'm seeing on the forum is Ap. agassizii. Others that you might want to consider are Ap. cacatuoides, Ap. borelli and Ap. trifasciata. The abovementioned 4 species are all very hardy and can be very colourful if you obtain quality specimens. Also, what you say about each apisto reacting differently is very true...except that this difference is not confined to species. even different fish within the same species can act totally different. that's one of the wonderful things about keeping apistos - your fish have character!
2. Tankmate wise, you may end up losing your shrimp. I've had very poor experiences with keeping apistos with shrimp, and every shrimp that i've ever kept in my apisto tanks have ended up torn in 2. Even large yamato shrimp the same size as my juvenile apistos were not spared. The apistos will just wait till the shrimp has moulted and has a soft shell before striking. The killies, lampeyes and galaxies should do fine though.
3. Your tank parameters look good for apistos. The ph is quite ideal and you'll be able to keep species beyond the "beginner 4" that i recommended above. Water current wise, as you know, i've recently upgraded to a Fluval FX5 in my 4x2x2 planted tank (yes, you're welcome to come take a look without the need for any food or fee) and the flow is acceptable in my opinion, especially since the plants will break the flow and provide cover for the fish.
Hope this helps you somewhat
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