Or use something like ES File Explorer File Manager from the Play Store or am alternative browser like Dolphin. ES has a downloader that is one of the choices when downloading a file from the web. In the ES settings you can set its default download location to the external card. Dolphin lets you pick the download location at each download. The TouchWiz camera and some others let you specify where to store photos.
Also, Titanium backup and other backup apps let you back up to the external card.
And most important of all, especially if you are crack flashing TouchWiz ROMs, keep your TWRP or CWM backups on the external card. They can be 2 GB+ each if you don't use compression, and not much better if you do. I have a 16 GB Nexus 7 and its a constant battle with backup space. I usually keep one solid reference backup and my latest only. I would love to be able to throw a 64GB card in it.