The ability for driftwood to affect your tank pH is greatly over rated. Some types will do it more than others and the greener the wood is the more of an effect. Small tanks with tons of wood will show it more than how most of us hard scape our tanks.
Braking is fine, if you can do it..or you could distress the cut surfaces to look more natural.
if you cut the wood with a saw and have a flat edge, you can position it at the side of the tank so it looks like it is branching in from nowhere or make that the base of the wood. most wood sits better with a flat base that is obscured by substrate.
Sure you can cut it or break it, but if you have malaysian driftwood, good luck trying to break it, it's extremely hard. It took me about 10 minutes to cut through a piece about 2 inches wide with a hand saw.