Some plants that will grow just fine as long as you have roughly a 10watt flourescent light:
- anubias (sometimes comes attached to terracotta pots, which make great caves!)
- java fern
- java moss
With anubias and java fern, you don't bury them, you tie them to something. The other ones, stick the end in the gravel and let it do its thing. Some plants NOT to get:
- gold ribbon
- mondo grass
- purple temple
These are all semi-aquatic and will die.
Some great tankmates for a ten gallon:
- pygmy cories
- ember tetras (small, peaceful, non-nippy, relaxed swimmers, not at all frantic). In a ten gallon I prefer them to neons.
If you do choose to add fish after you have decorated, I would remove Triton first, add in the neons, then put Triton back in. If you can, re-arrange the decor. This should help him feel like it isn't his tank and hopefully reduce any territorial issues. It won't help if he just plain doesn't like company, though.
Hope this helps. :)