Thanks for your input. A couple of further thoughts. If I set up Thunderbird with a Gmail account:-
(1) Does this negatively effect the download/upload speeds for receiving/sending emails into and from my Thunderbird inbox and sent folders, compared with the speeds into and from similar folders on Gmail alone? If it there was a negative aspect, there may be advantages in doing without Thunderbird.
(2) Do I still need to copy to Gmail the emails in the sub folders in my Thunderbird/Profiles/xxxxxxxx.default/mail/pop3.paradise.net.nz? I assume that in setting up Thunderbird with Gmail, Thunderbird will automatically create another Profiles folder with a /mail/IMAP.gmail.com sub folder. If this is the case, could I then just set up my old "Hold" etc folders under the new /mail/ folder and move their contents over?
If you are adding your Gmail account to Thunderbird then you will want to add the Gmail account as IMAP. This should be the default option offered by Thunderbird. The POP3 protocol does not support remote folders.
Once you have setup your Gmail account alongside your existing paradise account in Thunderbird, you can simply drag folders between Local Folders (paradise) and Gmail. This will transfer your 800 emails between accounts with a single 'drag and drop' while preserving which folders they are filed under. I have transferred inboxes with many thousands of emails successfully on a standard fixed line broadband connection so unless your emails are especially attachment heavy this should not be an issue.
Thanks for the advice on exporting contacts. Here is a couple of slightly more trickier queries.
Firstly, I have a large number (~800) old and current emails saved in several sub-folders such as "Hold", "Sent", "Inbox" and "Retain" in my Thunderbird/Profiles/xxxxxxxx.default/mail/pop3.paradise.net.nz folder.
Is there anyway of copying these emails across to Gmail on a folder by folder basis, presumeably into Gmail's Inbox and related folders area, rather than doing it separately one email at a time, which seems to be what Vodafone is proposing? In reality with the number of emails involved, this would be an almost impossible task.
Secondly, what is the preferred option for handling emails in Gmail - Pop3 or IMAP?