My personal experience.
As for the 58, I'd say that the '08 model was better with a 7,0 than the '10; '10, I'd rather say is good for 6,0 - 7,0, the latter being its larger "performing" sail size. '09 can't say, but '09 boards in my view were slightly more powerful than '10 ones.
58 and 66 are perfectly matched, with good overlap over the 7,0 size. In fact, I had 58 and 66 in '10 and have both again in order for '11 (+ 75). By the way, I am selling my '10 66 (see
viewtopic.php?f=8&t=51360). Anyhow, '10 58 is definitely an high wind board. The difference going from 58 to 62 is raher big, it's not only the 4 cms. overall width, but also the tail width (+ 5 cms.) and the distance between rear straps that grow more than proportionally, making the 62 a much more powerful board. I would not advice for a 58 + 62, 2 boards, quiver (as one would get better range with 55 + 62 or 58 + 66); but in my view
both 58 and 62 could nicely fit together into a larger 3 or 4 boards quiver (i. e.: 58, 62, 66 and 75 for 6,3, 7,0, 7,6 and 8,4 respectively, 1 sail for each board, perfectly matched).
As for fins, I'd advice Talon 38 to 42 for the 66 (in 9.0% thicknes!!!). I mostly use my 58 with Falcons 32 to 36, but I know it's a bit too weird to advice that.