To put a announce is simple, you just need this script command:
announce "<text>",<flag>{,<fontColor>{,<fontType>{,<fontSize>{,<fontAlign>{,<fontY>}}}}};
Just add the 'announce' after the 'getitem':
Now, about show a countdown timer...
You'll need to remake the script, changing 'addtimer' to other function.
I suggest you look at 'doc/script_commands.txt' file or look for one script with hourly reward to get a example.
Good luck.