No, Apple doesn't approve your company first. You simply sign up as an individual or as a company and then you get to generate certificates which you can then use to sign any application you want.
And by default, you can simply hold down a shortcut key to open an application and install it anyway without a signature.
The point is this: if malware is published using your developer certificate, then Apple can simply revoke the certificate and by default, users won't be able to install or run your applications anymore.
As for the shortcut keys, they're documented, so you don't have to remember them.
And by default, you can simply hold down a shortcut key to open an application and install it anyway without a signature.