If you want a Male betta, I dont recommend getting the neons, they may not last long! Corydoras are a good addition to a tank with a betta, they seem uninterested in each other. The rasboras are a good choice. I would add to their number, add about 6 corydoras and the betta last.
if you realy want a male betta then have a back up tank just incase, some do well in communities others don't, most betta keepers on here keep them in seperate tanks with only cories or ottos as company