A 10g tank would only support 2 or 3 nerites. There is no difference in nerites except size and speed. Horned nerites are good for small tanks and I love their shell shape. Olives are mid sized and most commonly found. Tigers grow the largest but have the most variet in color and shell pattern and tend to move slower but do the job just as well as the other varieties. I have olive and tigers in my 220g and would have horned, my personal favorites had them been available when I got the others in.
Nerites eat bio-film, diatoms, green dust algae, and green spot algae. They do not eat thread or beard algae. Shrimp on the other hand do eat thread algae which amano shrimp being IMO the better choice of shrimp for hair/thread algae issues.