Is there an Idiot's Guide about switching from POP to IMAP?

[#1]

Bloke from Lancashire in peace.
Have just moved over from Wanadoo/Freeserve/Orange/EE or whatever the broadband thieving Frenchmen are calling themselves this week.
Set up my plus.com account as a POP mail account as that's what I've been used to but as I have a fistful of mobile devices ( laptop running XP, a couple of iPods and an Android smartphone ) it looks as if I'd be better off with IMAP - especially as deleting the same emails from every device individually is becoming a pain in the nuts.
I plan to keep the Wanadoo/Freeserve/Orange/EE POP account running for the moment until folk catch on to my new plus.com address but will only access that from my desktop PC at home. ( WinXP3 ). The laptop and the mobile devices will only need to connect to the new PlusNet account.
Dumb questions follow, logic being that it's better to ask a dumb question and appear stupid than it is to not ask the question, then do something dumb and remove any doubt.

(1) Can I just switch the settings on my devices from the POP servers to the IMAP servers or do I have to set up a new IMAP account?
(2) What will happen to the emails that are on the Wanadoo/Freeserve/Orange/EE POP server?
(3) What happens to the dozens of folders, settings and rules I have set up on Outlook? How will they appear on the screen of each mobile device?

[#2]

1. yes
2. They will be downloaded by the pop client. You need to set it to download and delete if you want to remove them,
3. Nothing, the rules only work on the client. However once the rule has been run the message moves to where ever the rule has put it, so if you have a rule that moves all messages from the orange pop download to a folder called orange then after it has run ALL the devices using imap will see the same messages in that folder, however NEW messages will only be moved when you run outlook.
Been many many years since I used pop so not up to date on it, but basically, it should have been delete on one deleted on all - but only if you hadn't already downloaded it on to the other devices, if it was already downloaded but not deleted then it would stay on the other device. Imap maintains ONLY one copy of the messages (unless you keep a local offline copy) so they should see the same thing,

[#3]

Thanks,
Love the cookery books, by the way.
Did that mean "Yes you can just change the settings" or "Yes to have to set up a new IMAP account"? ( I'm guessing the latter as I can't see any way on changing the settings on my existing Outlook POP account )
I have set up an IMAP account on my laptop as a trial run, am I safe to remove / delete the POP account there - assuming all my old e-mails are stored on my PC?

[#4]

Set up an new account with imap as the type, you will be changing the suppler anyway (from orange to pn)
Don't delete anything yet, until you are sure you have everything you want.

[#5]

OK
I now have two iPod touches and an Android phone that are IMAP only and are picking up test messages sent from my old Orange account perfectly 
The laptop ( Outlook 2003, Windows XP3 ) is collecting the test message via IMAP but still displaying the old POP mail folder structure.  It has set up a new mail folder labelled "Plusnet IMAP Account" which I've moved in to my "Favourite Folders" pane.
Clicking on the folder name opens a dialog box reading
"Unable to display the folder. This is the root of an IMAP store. The root does not contain messages but may have subfolders that do. To see messages in the subfolder. display the folder list, and then click the subfolder."
So I did, and it did, and there was my test message.
Seems a bit clunky.
How do I set things up so that incoming IMAP messages go in to the default "Unread Mail" folder?
Am I right to assume that a message that has been read on another device ( say, my smartphone ) will go to my regular Inbox and not the "Unread Mail" folder?

[#6]

You need to be careful given the difference between POP and IMAP.
With POP, everything is downloaded to your local system and all changes occur there, and only that device can see the email.
With IMAP, everything stays on the server, and can be seen on multiple devices  (including the read state).
If you set up client side rules which move messages from the inbox to a local folder, all other devices will lose access to those message.
You can create additional folders on the server and have the messages moved to those,  but that would only happen when the right client is used, or each client needs the same rules.
If you do want to separate your read and unread messages into different folders, it'll be better to move the read mail, as all new mail will appear in the Inbox.
Also, depending on the clients and your requirements,  you may need to set the clients to save sent mail to the server too, otherwise the sent mail may be stored locally on each device (and only on the device which sent the message).

[#7]

So would the answer be to delete all the rules currently running on Outlook and start afresh?