Is it possible to have IMAP on phones and POP3 on laptops configured as required for each email address?

You can configure each device that is connecting to your Hosted Exchange Mailbox as per your own preference. So if you want IMAP on your Smartphone, then simply configure the phone appropriately, likewise if you wish to use POP3 on your laptop or desktop simply configure the client application appropriately.

However if you intend to access your mailbox from different devices we would recommend connecting using "Outlook Anywhere", as this will give you access to your address book, calendar etc. Please be aware that Outlook Anywhere is only available on the "Hosted Exchange Starter" option and above.

You can enable POP3 or IMAP support on an exchange account and see the details you need to use in http://cp.blacknight.com under:
Exchange >> Mailboxes >> email@address.com >> Edit