I think the Land of Light gets fleshed out little by little with each Ultra series. They actually show more of the country in the Ultra Galaxy movie (well, I don't remember the exact title, but it's the one with the last appearance of Mirai). But my impression is still that all the Ultras do is fighting/training or if he/she is the blue scientist tribe like Hikari, works in a lab or something. While I'm sure they have more of a life outside the two things I list, I assume the Ultras don't need money since they don't seem to have needs like humans (or some other aliens) do.

You are probably right that people just pretend not to know Ultraman's identity. I like to hope that people being smart but just keeping quiet is the case, anyway. (The ones admitting they keep Ultraman's secret usually do it for good reasons: for the human host's protection, fearing he would go away if he knew they knew. But maybe some might just want to keep the host from being embarrassed like you say. ^^;) And sometimes, that actually happened: each person didn't know the other person knew the truth, and tried to hide it from each other to help out the human host. I always love seeing that. Or a variation which I also like: one person (or a few persons) knew the truth, addressed the human host as Ultraman, and had to think of a terrible excuse (usually puns) when unrelated/clueless people showed up overhearing part of the conversation (the "Ultraman" part).