> We want to select only the best technical people (i.e. no business guys).
Problem 1: Bias
Problem 2: "Guys" (no feminism here) should actually be "teams" (even if they're all 23, white, male)
> what are the best questions I should ask people in order to gauge their technical aptitude and general awesomeness?
Doing this won't get you anywhere. You are a business accelerator, not Amazon hiring a genius who writes assembly that can squeeze out an extra 2% on their servers.
You should be evaluating teams (most important), their execution (also important) and their idea (least important but very valid).
Personally, I don't think you should be doing the interviews on your own, or if everyone thinks like you, should probably get experienced entrepreneurs to do it instead.
Please note that I am not insulting you or any of your abilities. It just seems that you have an ingrained technical bias and you may recruit highly-talented tech people but most of their ideas are shit and your accelerator will bomb-out soon.