Is there a general way to tell if an installed app is 32-bit or 64-bit?

And if I'm on 64-bit ubuntu, do 64-bit versions of apps automatically get installed if there is one available (using the sudo apt-get install)? I.e. is apt-get intelligent enough to figure out that the 64-bit version is probably what I want, or do I need to set an extra flag or something to get the 64-bit version?

I recently installed imagemagic using the following command:
sudo apt-get -y install imagemagick

On the imagemagick website it offers different types (low memory version versus higher accuracy one) and you can download the appropriate .rpm. Presumably this choice is also available through apt-get. Is there a way to query what options for install there are available through apt-get? Or is it more usual that apt-get can only install one thing and you need another repository or something to access a different version of the app?