Olive nerites do lay eggs in freshwater - but they are not viable unless in brackish water. I've thought of trying to breed them too - they are such great algae eaters! To add to the plant list bacopa monnieri, many anubias species, vals, hornwort, java fern & water sprite. But I bet lots of plants that have waxy leaves would be able to adapt to a brackish set up - oh yeah sagittaria will work too! I've also had green rotala, and rotala indica in brackish water and it was fine, although grew as though it was put in a shrink ray - it had lots of growth but it was mini! Maybe it was dehydrated? When I put the plants back in fresh water they went back to their normal leaf structure.
are you planning to use a soil underlayer with crushed coral gravel or sand on top?