I don't use campden tablets or heat pasteurization. I just wash the fruit thoroughly and remove any pieces which are damaged or look like they are starting to turn. I've done it many, many times and never had a problem with infection.
My first few times making fruit beers, I did make a puree and heat pasteurized it. The flavor I got from that was different from that of fresh fruit. Sort of like the difference between cherries in a cherry pie vs fresh cherries, I guess. I prefer the unheated version, personally. I usually cut up the fruit (or "distress" it in the case of blueberries, raspberries, etc.) and put the fruit in a sanitized container to freeze, then put the frozen fruit into a fine mesh bag (e.g. hops bag) when I put it in secondary.
So far as clarification is concerned, I had some problems with pectin haze when I did the heat pasteurization. Adding pectin enzyme didn't help very much to improve clarity. With fresh fruit, I use my standard whirlfloc in the boil, and a cold crash with gelatin addition after secondary. My fruit beer comes out crystal clear.