I will soon be uploading a new app to the App store. I have a question concerning the build version of the app. Does Apple still allow us to upload an app that has been build for iOS 7, since I know Apple is kind of forceful about staying up-to-date. I can't find anything about it while googling.
The deployment target is the lowest iOS version your app is supporting and Apple doesn't limit that (AFAIK). So if you want to (and are able to), you can still submit an app that runs on iOS 5, for example (iOS 5.1.1 is the newest iOS version for first-generation iPads).
Apple does specify the lowest acceptable Base SDK (the libraries you're linking against) when submitting, though (they change this every few months/years and announce this to developers via e-mail). If you're using the latest non-beta Xcode, you're always fine. Submissions from Xcode beta version are never accepted.