Assuming the present fish are remaining in the 30g (except the last two to be re-homed), you haven't any room for more fish. Check the profiles for details, esp Swordtail. Swordtail's natural habitat can be replicated with fine gravel (not sure what you have now, may be suitable if it is a natural or dark mix) or sand, river rock as boulders, some bogwood; remove the marbles.
If you want to replace the existing filter, I would look at the Fluval U-series, internal filters. Plants like Corkscrew Vallisneria (loves medium hard water, essential for livebearers), dwarf sword; Floating perhaps Brazilian Pennywort. All are in the profiles, click shaded names. Light--what do you have now for a fixture?
On the 10g, what are your tap water parameters (GH, KH and pH)? There are some nice options with small fish, but some of these are wild caught and more specific with respect to parameters. Gourami will restrict you to the rarer small species in a 10g, the sparkling gourami, licorice gourami, eyespot gourami, but these all need soft water. There are several dwarf species of rasbora (Cyprinids), the Scarlet Badis (Badidae), etc. Plants could be crypts, with Water Sprite floating.