Something to research a little bit first and you my need to contact your host for this:
* Deprecated PHP version (PHP4)
You will want to be running PHP5 for the newer stuff. PHP4 works, but PHP5 works better.
Also, be sure to backup your old site as well...the new one might work great locally, but on the server might have an issue or two.
My suggestions for a "replace site totally" case:
Create a new database that is empty and the new site can use.
Create a directory where your new site is going called "OLD" or whatever you prefer, and then move all the old site files to that directory...this way you don't have any interference from them while you are uploading and installing the new site...but you also don't take them totally off your server just in case you need to replace it in an emergency.
Now, upload all your JoomlaPack stuff and when you run the install, be sure to use the new database info as it won't want to overwrite the old database...or it will create more new tables with a different prefix and you'll still have all the old info there that's not needed. New is best.
The errors it looks like you are having are that your server is running PHP4. It may have PHP5 installed and be able to run it and it just kept your site running on PHP4 since it was installed on PHP4. Ask your host before you do this if you can.
The other one seemed like there were just other Joomla files there when you tried to upload all the JoomlaPack files. With the old site in this "OLD" directory, I think you'll be fine.