Nice, I'll be tagging along with this one as well. Enjoy these types of tanks a lot, as they typically end up being more "natural" in my opinion than the typical fish tank. I've found SACHS to be a good source as well;
Amphipods (hyallela azteca) for sale at Sachs Systems Aquaculture
Many "bugs" should not be fed to aquarium fish, things like water boatmen, backswimmers, water striders, etc. which are often found in buckets and/or outdoor pools are best not fed. Most are too big for typical aquarium fish to handle, and some such as predacious diving beetles and their larvae, giant water bugs, dragonflies and damselflies can in fact harm fish or other invertebrates in the aquarium.