As I've said before I can't find a definate answer on the gestation period. Signs you should be looking for are extremely swollen stomachs, eating ravounously then almost stopping altogether. And in the late stages of pregnancy as mentioned before a small black patch (gravid spot) under the anal fin. Personally I wouldn't use anything in the breeding net, just keep an eye on her, once she's had the fry remove her.
Then you'll have to decide what you want to feed the fry on. I would recommend freshly hatched brine shrimp to start with then move on to crushed flake within a few weeks. Different people raise young on different foods, there's no right or wrong food really it's personal preference.