Yes some red would definatly help in this tank IMO, i would go with the L.arcuata, i dont dose extra iron and it colours up nicely for me, i think the Rotala rotundifolia needs low nitrate levels rather than extra iron to colour it up otherwise it grows quite green.
What type of moss are you using? it looks a little messy if you dont mind me saying
I have to agree Ottos are some of the toughest fish i have kept as well, i think once they survive the initial period in a tank they will live a long time, although how much impact they auctually make on algae in a tank is debatable unless you have lots and lots of them.