I would skip the Eco-complete. Also, the laterite will provide iron so be careful how much you dose in the water.
For plants, just about anything will work. I'm using HC, Crypt parva and S repens in the foreground. Blyxa japonica and misc crypts in the middle with various stems in the background. Personally, I think smaller leaved stem plants work better in a 55 gal. Rotalas, Bacopas, Hemianthus glomeratus, several of the Limnophilas also work well.