Hi tinah, you seem to be a careful fishkeeper, glad to hear you are taking your time to do this right.
One or two Nerite Snails would make your tank a lot of good as they keep algae in check. They have a relative small
bio-load, say 1" each.
Ghost Shrimps, on the other hand, have virtually no bio-load but I have no clue if the Bleeding Heart Tetras would tolerate them or not since they are carnivorous. If they do, you could go for a Nerite Snail and three Ghost Shrimps.
That would leave your tank with a bio-load of 11 or 12" for 10gallons, actually a bit higher since the substrate, plants and decor displace some of the 10gal volume of water, so keeping a thin substrate might be a good idea. As far as you keep good maintenance routine, and provide adequate filtration -which your biowheel should provide-, I don't expect you to have any problems whatsoever once your tank is stable.
I keep some overstocked tanks as most of my fishies are growing up and I aim at
MTS big time, but I don't recommend this to others, since it implies more costs (e.g. multiple filtration systems, higher energy bill as well as being ready to set larger/more tanks short term) and could push easily into more frequent water changes.
I wouldn't go for the small sized corydoras (e.g. Adolfoi, Pandas, Bronze) since they usually are schooling fish, and add 2.5" each.
If I may ask/suggest: Are your light lamp(s) fluorescent or incandescent? If fluorescent you seem have a lot of light there (3.0WPG), consider downgrading to half (1.5WPG) in order to achieve two objectives:
1) avoid algae bloom problems (go with low-light plants), and
2) Bleeding Heart Tetras are kind of shy and bright lights might stress them.
Pepe
Santo Domingo