Best solution for my home based business?

Looking for some guidance on what set of software/subscriptions would be best for my home-based business. Here's what I have now:

-- My website hosted with squarespace
-- My email is currently a free POP service offered by my domain registrar
-- My calendar and contacts in Google
-- Laptop (PC)
-- My tablet is ipad
-- Blackberry Curve 9320 (go ahead, mock it – yes it's a creaky dinosaur but I love the small size and durability)

My primary objectives: 1) Real-time seamless syncing of e-mail (IMAP) and same for my calendar and contacts across all devices above. 2) Will work with my blackberry 9320 (google seems to have stopped blackberry support, so assuming signing up for google apps for business would not work out well for me...). 3) Price. But don't mind paying for solution that works and dependable though.

Here's what I am considering: 1). Buy Microsoft Office 365 University edition, as my partner is student and it is less than $100 for 4 years. 2) Given 365 University does not include custom domain support/can't connect my current custom domain e-mail address, was going to also buy the standalone Microsoft Exchange "Online Plan 1" (approx $4/month). 3) Point my laptop/ipad/blackberry mail and calendar settings to the Exchange server.

Given the above, any problems you foresee? Any other options/vendors I am missing? Thanks so much!