My (very) brief G-search suggests that a pst file contains email not contacts. If you use IMAP you don't need to migrate emails, TB will simply re-sync them from the server. Start with TB empty, set up the accounts, and wait...

Your OP said you want to convert 'contacts etc'. What's 'etc'?

I suspect you're looking in the wrong place for exporting contacts. And how can a contact have >56 data items? Maybe theoretically...

If it does, load the csv into a spreadsheet, highlight all the empty columns or ones that hold this junk, and delete them. At the same time delete any email addresses you don't recognise; many email systems 'collect' addresses of emails you've been copied on. (TB does, but it keeps them separately as 'collected addresses'.