what do you meant by BETA? there are lot of sites in beta..no big deal..you can put it as long as you have some reasonable content..
i thing google will not accepted site which is under construction or with very less content if your site has few pages and navigation does not have broken links then there is no problem
Sure you can, if you have some content there. Just put something up. And make sure not to "test click" your own ads, just to "see if it's working".