404 re-direct help.

[BasilFawlty]

Hi all,
I found THIS THREAD about the 404 redirect script and have downloaded the script and "think" I understand how it works. Apologize for starting a new thread, but I saw that the existing thread has a post that was back in May and no one replied, so I felt I'd start a new thread because I really need to get some questions answered. Hopefully many of you have used the 404.php script and can help me out. I've been running ebb,threads for 12 years but recently purchases VB and plan to migrate in the next few weeks (months?). Like many I'm sure, one of my biggest concerns it how to get the old links in Google to re-direct to the corresponding new link (thread, post, etc). I downloaded the 404.php script and went through and configured it for my site, but have some question before I actually migrate my old forum to the new VB install. I know some of these questions probably will seem lame to you experts, but here goes:

1. The script calls for creating a table called 404_actions and has the query to do that. My question is, am I correct in assuming that this table gets built in the new VBulletin Database?

2. Does the table need to have the VBulletin table prefix I established when I did the install? In other words, does the table need to be called vbb_404_actions (assuming my table prefix is vbb_ )? Or do I simply create a table with the name given and don't worry about the prefix?

3. Where does the 404.php script that does the re-directs get installed? I have my standard 404.html file in a directory like this: /errors/404.html and then in my .htaccess in my root directory I have:
ErrorDocument 404 /errors/404.html which works great. But when I upload my 404.php "script" where does it go and how do I tell my system to access the 404.php file to do the re-directs and the 404.html file only when a different non-existant page is accessed?

I think these are my main questions for now, but IU'll probably have more as I get closer to zero-hour.

Thanks in advance.