The final piece of the puzzle: in File, Options, Advanced, you can set your "real" Inbox to be the default start up folder. After you set up the account in Outlook, move your appointments and contacts to the data file folders. If you are using an IMAP account in Outlook 2013 or newer, close Outlook and delete the IMAP account's data file.
In File, Options, Mail, look in the Send messages section about two-thirds down for Always use the default account when composing new messages.
Set your email account to be the default on the Email tab.
Set the account to be the default data file on the Data Files tab.
This puts the calendar in the To-Do bar and new appointments and contacts will go into it's Calendar and Contacts folder. If you want to remove the calendar and contacts folder from the your "real" account uses, see Delete Special folders.
You can use this method for instance to import holiday updates or custom holidays or vacation lists provided by your company.
When you create a hol-file of your own, make sure you save it in the Unicode format (use the Save As… Note 2: If you are using Outlook 2000 or previous, then the holiday definition files are saved in a txt-file and the default file is called Because of the txt-extension, the aforementioned double click method will not work.
If you enabled two-factor authentication on the account, you'll need to generate an app password to use with the account in Outlook.
Log into and check your account options for instructions.
Most ost to pst programs can recover them if you have a copy of the old data file, but removing an Exchange Active Sync account will most likely delete the associated ost file. This works with Outlook 2010 and above with Exchange accounts to sync your calendar and contacts with other computers or smartphones "over the air" when your personal email account is POP3 or IMAP.