I want to download the Starcraft 2 trial as a .dmg or a .app file so I can load it onto a usb and plug it into a computer that has slow internet access. Is that possible?
You should be able to copy over the entire
Applications\StarCraft II\ folder from one Mac and move it to another Mac and play it there, without needing to reinstall the game.
If you are playing offline, your saves are in:
"Users/[computer user name]/Library/Application Support/Blizzard/Starcraft II/Accounts/[account name]/[number]/saves"