Ok, second try at posting this.

Thanks Puma for posting the link.

now I dont have to.
From my knowledge on mollies is that they like to have their room to swim around. I am from the old school and like to keep them in larger tanks, 20 gallons or larger. The more swimming space the better. This also goes for swordtails. I
I have had some males of the
Poecilia sphenops, what is known as the black molly even though their natural color is siilver
Picture is below , grow to be about 3 inches in length. I believe they have been crossed bred with the Sailfin molly. This is why we do find them to be a bit larger than the wild form.
here is a picture of the florida sailfin molly,
Poecilia latipinna. There is a mexican species
Poecilia velifera , which is the largest of the species of mollies.
As for bottom dwellers, you should be fine with what you have. I have kept cories with many of my livebearers and never had a problem. Another great cleaner I love adding for diversity is the Amano shrimp. They do a great job at cleaning alage along with the mollies. They love to munch on alage. A great food for them is diced up zuccini.
Here is a list of Great live bearers for a 10 gallon.
Guppies
Endlers
Dwarf livebearer/least killie fish
Heterandria formosa, view my avator for a picture.
Merry Widows
Platies
These guys make great fish for any 10 gallon tank and are great community fish too.
jim