Our contractor seems to think the pressurized wood is just fine as it is and will need nothing for 25 years. We won't live that long, soooooooooo

I just finished redoing my old cedar deck. It had developed surface cracks all over. A few were cracked all the way through and I had to replace those. But for all the rest of the deck I found a product called Elmers oudoor wood filler that was stainable at Lowes Hardware. I had a kid sand and renail those boards and fill the cracks with that product. Then he resanded the filled places and stained the deck. I can tell you it was a ton cheaper than replacing the deck boards (the few I replaced cost me $400 for about 12 boards about 12 feet long in construction heart redwood). The filler doesn't match perfectly but at the age of my deck it looked fine. I used Cabot's Australian Timber Oil in flame mahogany. Everyone comments that it looks great.

Read the installation instruction for the PVC deck you decide to work with. From my experience PVC decking feel better on 12" center framing. We always tear out the frames and start with a new, flat, and properly constructed frame. Old frames take significant amounts of work and time to prepare for a quality installation. The frame is a critical aspect of having a good looking end product. Do it right, it will last a lifetime.

"How would I go about removing the screwed in boards?" If the screw gun doesn't work, rip the board between the screws and remove the center. Pound a wrecking bar between the now-exposed joist and bottom of the screwed board and pry. If the screws are tearing up the joists too badly, sever them with a Sawzall first.