Thanks for your answer. Good thing I'm not alone out here

2. a/b) The general idea for these two items is that you'll need to transfer all your web content from the shared server to the VPS. The FTP account on the VPS will be created with your lunarpages username, so it should be the same aside from the server IP. It is not required that you ZIP the files after downloading them from your shared account and reuploading them to the VPS account, this is simply something that can save you upload time. Whether you zip the files or not, they will need to be downloaded from public_html and reuploaded to the httpdocs folder on the VPS Plesk account. httpdocs is the equivalent of public_html on cPanel. As for databases, both cPanel and Plesk have phpMyAdmin as a feature which you will be able to use to both export and import your MySQL databases. This is not a very difficult process and we can provide assistance if needed.
About the FTP process: public_html will be called httpdocs? What about the files outside of public_html? I have a ton of them. They'll still allow me to create directories from / ?
This would also mean some scripts that use full path (I have a few) would need to be changed from 'public_html' to httpdocs'
c) Unfortunately this will not work. Not only will it not create all the proper entries, but due to the fact that some of our machines run in the maildir format while others run in the mbox format, you may not even be able to copy inbox files/directories between the two if they differ in their mail storage format. Furthermore, Plesk does not utilize the same folder paths as cPanel for some things. Therefore if you choose Plesk we only recommend recreating the mail addresses unless you have experience working with mail systems and mail transfer agents, specifically Exim (cPanel) & QMail (Plesk).
Wow this would take some efforts on me and my users. What is a working process that people use to do this without disrupting their mail users?
What about the webmail interface? Will
http://www.mydomain.com/webmail work?
d) Parked domains would need to be re-added through the Plesk control panel, although it as simple in Plesk as it is in cPanel. Again, we can provide assistance here if needed.
OK. I'd imagine I won't be able to test these untill the DNS switch is made. Do I need to unbind (unpark) the parked domains from the Cpanel of the existing Shuttle account first? Or can I park them on the new server while the old ones are still working on the Shuttle account. Then when the DNS switch is made (ns1.lunarpages.com -> ns1.mydomain.com), the parked domains would automatic switch over? The reason I ask is that I'm trying to figure out the best way to minimize/elimiate service disruption to the users who use the parked domains. Is it possible?
e) No other configurations should be required, although you should make sure if you have a suPHP_Config variable in your .htaccess file that you remove it as we do not utilize suPHP for Plesk.
Good to hear. What about Cron jobs? Are they stored in some sort of files? Will they be transferred over with the FTP processs, or will I have to recreate them?
f) The Plesk control panel does support a "site preview" option which allows you to view the site before DNS propagation. Pointing a temporary subdomain at the VPS account is also an option. The issues that can occur here are hardcoded URLs (i.e. img src=www.mydomain.com/image1.gif ) that try to load things using the domain name, which would still be directing to the shared account. Also mod_rewrite rules in .htaccess that are dependent on domain name functionality will also not function until the DNS has propagated to the VPS account. If you're unaware of what mod_rewrite rules are, you most likely have not implemented any.
Once you're confident you have transferred all content over successfully and that it is configured properly, you will need to both register your private nameservers and also replace ns1.lunarpages.com and ns2. lunarpages.com with your private nameservers. They are two different steps. You can register the private nameservers ahead of time and swap them out with the lunarpages nameservers when you are ready for the domain to begin propagating over to your VPS account. This should be seamless as for a period of 24-36 hours the domain will resolve to either the shared account or the VPS account, and both will still be active during this time.
I called my registrar today and they said as soon as I get the IP address, I can just call up and register the private name server. I figure I would do this before anything else. Then when I'm done testing the new server, I'd would point all the domain names's DNS entry to the newly registered private server. Do I need to 'park' them in the Plesk control panel before I change the domain names' DNS entry with my registrar? Which step should be taken first?
We will keep your old shared account active until you have informed us that everything has propagated over to the VPS account and you no longer need it. If you forget to reply back to us, we will e-mail you asking us to update us on whether or not it's okay to close it out before removing it.
That's really good to know. There's a lot going on on my site and I'm also very anal on top of that. So I figure I'd need to run 20-30 comphrehensive tests before I can be sure the new server is working OK. I think I'd need at least 3 days for myself before the DNS switch.
Thanks again.