Delhezi Bichir ( would go quite nicely as it is a bottom dweller). It grows quite slowly and is quite cute. Beware, once you have bichir - pleco will be out of question due to incompatibility.
Not necessarily true. I have a mango in with two senegals and a chocholate and a royal in with the ornate without any problems. Anything that isn't extremely aggressive and doesn't fit in the aro's mouth should work. Mine is currently at 12 inches with an equal size BGK, two senegals, a large angel, two pimodella gracilis(used to be three), the mango pleco and one probably soon to be doomed long finned rosy barb.