how do i load my old game file? would i just transfer the save file from the old version to the new?
The best thing to do is delete your old HH and install the new version. Your saves are stored in appdata so deleting the game wont effect your saves.
Overwriting the old files is actually a very bad a idea, and can easily break your saves. Overwriting an old script with a new one can end up deleting or adding extra parts of the script.