Trust me when I say you will want to keep your SuperNET in your NXT wallet. You can also go ahead and use the early beta SuperNET wallet but remember that it is beta and not all functions are there yet. Coinomat works along with the production server MGW. https://nxtforum.org/lite-multigateway-releases/supernet-v1-3-4-3/

As for dividend payments. SuperNET pays out asset dividends for services that is being funded with use in SuperNET. In the future any other services that SuperNET funds will also be payed out as asset dividends. All these funded assets also can be traded separately through the NXT asset exchange located in the NXT/SuperNET wallet. SuperNET also buys up large amounts of asset it finds profitable to invest in for it's holders. Because of this SuperNET will also pay out dividend in NXT since all the assets it holds is receiving NXT fees from people using the service. The fees from these services is much small compared to  the more centralized counterparts to encourage usage. The more users of SuperNET the more fees to be payed out and the higher the NXT dividend is received. As for when SuperNET will start to pay out dividends in NXT? I'm not sure. Only the people in charge know that.