You will need to enlarge the hole in the pickguard and the pocket in the guitar body to accomodate the humbucker. Some skill is required to get clean-looking results.

Electronically, you can simply swap the pickups and retain the stock wiring, or add Series/Parallel selection to your palette. The stock Strat 5-position switch already has out-of-phase connections (positions 2 & 3), and you may want to add another tone pot. You might consider a Master Volume with separate Tone pots instead of the stock arrangement.

The sky's the limit. Do whatever you think will work best for you. Even if you change your mind later, you can re-arrange things to suit yourself.