AppleScript: how to open the terminal fullscreen and execute commands
You need to be talking to Terminal, not window 1. This script worked fine for me.

tell application "Terminal"
    activate
    tell application "System Events"
        keystroke "f" using {control down, command down}
    end tell
    do script "cd ~/Downloads" in window 1
    do script "brew list" in window 1
end tell